diff --git a/PowerEditor/scintilla.original.forUpdating/lexilla530.zip b/PowerEditor/scintilla.original.forUpdating/lexilla531.zip
similarity index 60%
rename from PowerEditor/scintilla.original.forUpdating/lexilla530.zip
rename to PowerEditor/scintilla.original.forUpdating/lexilla531.zip
index 9783b7213..c49f2c8c6 100644
Binary files a/PowerEditor/scintilla.original.forUpdating/lexilla530.zip and b/PowerEditor/scintilla.original.forUpdating/lexilla531.zip differ
diff --git a/PowerEditor/scintilla.original.forUpdating/scintilla541.zip b/PowerEditor/scintilla.original.forUpdating/scintilla542.zip
similarity index 69%
rename from PowerEditor/scintilla.original.forUpdating/scintilla541.zip
rename to PowerEditor/scintilla.original.forUpdating/scintilla542.zip
index 163077b4d..513c8a305 100644
Binary files a/PowerEditor/scintilla.original.forUpdating/scintilla541.zip and b/PowerEditor/scintilla.original.forUpdating/scintilla542.zip differ
diff --git a/lexilla/.gitattributes b/lexilla/.gitattributes
index 0e7df5010..2f851b2b8 100644
--- a/lexilla/.gitattributes
+++ b/lexilla/.gitattributes
@@ -29,10 +29,12 @@
 **.aspx text
 **.php text
 **.vb text
+**.asm text
 **.cmake text
 **.d text
 **.diff text
 **.erl text
+**.f text
 **.gd text
 **.gui text
 **.iss text
diff --git a/lexilla/.gitignore b/lexilla/.gitignore
index 438c50c2b..725ec83cc 100644
--- a/lexilla/.gitignore
+++ b/lexilla/.gitignore
@@ -1,6 +1,5 @@
 *.o
 *.a
-*.asm
 *.lib
 *.obj
 *.iobj
diff --git a/lexilla/cppcheck.suppress b/lexilla/cppcheck.suppress
index d12fbdf89..cb9bebce8 100644
--- a/lexilla/cppcheck.suppress
+++ b/lexilla/cppcheck.suppress
@@ -21,6 +21,10 @@ passedByValue
 // cppcheck 2.11 can't find system headers on Win32.
 missingIncludeSystem
 
+// Passing temporary string into hidden object creator functions: they do not hold the argument
+danglingTemporaryLifetime:lexilla/access/LexillaAccess.cxx
+returnDanglingLifetime:lexilla/access/LexillaAccess.cxx
+
 // cppcheck seems to believe that unique_ptr<char *[]>::get returns void* instead of char**
 arithOperationsOnVoidPointer:lexilla/lexlib/WordList.cxx
 
@@ -41,6 +45,7 @@ constVariablePointer:lexilla/examples/CheckLexilla/CheckLexilla.c
 // Suppress most lexer warnings since the lexers are maintained by others
 redundantCondition:lexilla/lexers/LexA68k.cxx
 constParameterReference:lexilla/lexers/LexAbaqus.cxx
+constParameterReference:lexilla/lexers/LexAda.cxx
 constParameterReference:lexilla/lexers/LexAsciidoc.cxx
 constParameterCallback:lexilla/lexers/LexAsn1.cxx
 knownConditionTrueFalse:lexilla/lexers/LexAU3.cxx
@@ -53,16 +58,20 @@ constParameterReference:lexilla/lexers/LexBash.cxx
 knownConditionTrueFalse:lexilla/lexers/LexBash.cxx
 variableScope:lexilla/lexers/LexBash.cxx
 constVariable:lexilla/lexers/LexBasic.cxx
-variableScope:lexilla/lexers/LexCmake.cxx
-knownConditionTrueFalse:lexilla/lexers/LexCmake.cxx
 constParameterReference:lexilla/lexers/LexCLW.cxx
 knownConditionTrueFalse:lexilla/lexers/LexCLW.cxx
+variableScope:lexilla/lexers/LexCmake.cxx
+knownConditionTrueFalse:lexilla/lexers/LexCmake.cxx
+constParameterReference:lexilla/lexers/LexCmake.cxx
+constParameterReference:lexilla/lexers/LexCOBOL.cxx
 constParameterReference:lexilla/lexers/LexCoffeeScript.cxx
 constParameterPointer:lexilla/lexers/LexCoffeeScript.cxx
 knownConditionTrueFalse:lexilla/lexers/LexCoffeeScript.cxx
+constVariableReference:lexilla/lexers/LexConf.cxx
 constParameterReference:lexilla/lexers/LexCPP.cxx
 variableScope:lexilla/lexers/LexCSS.cxx
 knownConditionTrueFalse:lexilla/lexers/LexDataflex.cxx
+constParameterReference:lexilla/lexers/LexDataflex.cxx
 variableScope:lexilla/lexers/LexDataflex.cxx
 knownConditionTrueFalse:lexilla/lexers/LexECL.cxx
 variableScope:lexilla/lexers/LexECL.cxx
@@ -75,6 +84,7 @@ constParameter:lexilla/lexers/LexFortran.cxx
 constParameterReference:lexilla/lexers/LexFortran.cxx
 redundantContinue:lexilla/lexers/LexFortran.cxx
 knownConditionTrueFalse:lexilla/lexers/LexFSharp.cxx
+constParameterReference:lexilla/lexers/LexGAP.cxx
 constParameterReference:lexilla/lexers/LexGDScript.cxx
 variableScope:lexilla/lexers/LexGui4Cli.cxx
 constParameterReference:lexilla/lexers/LexHaskell.cxx
@@ -83,6 +93,8 @@ knownConditionTrueFalse:lexilla/lexers/LexHex.cxx
 constParameterReference:lexilla/lexers/LexHTML.cxx
 constVariable:lexilla/lexers/LexHollywood.cxx
 variableScope:lexilla/lexers/LexInno.cxx
+constVariableReference:lexilla/lexers/LexInno.cxx
+constParameterReference:lexilla/lexers/LexJSON.cxx
 constParameterPointer:lexilla/lexers/LexJulia.cxx
 constParameterReference:lexilla/lexers/LexJulia.cxx
 knownConditionTrueFalse:lexilla/lexers/LexJulia.cxx
@@ -108,18 +120,24 @@ constParameterReference:lexilla/lexers/LexNimrod.cxx
 knownConditionTrueFalse:lexilla/lexers/LexNimrod.cxx
 variableScope:lexilla/lexers/LexNimrod.cxx
 variableScope:lexilla/lexers/LexNsis.cxx
+constParameterReference:lexilla/lexers/LexNsis.cxx
 knownConditionTrueFalse:lexilla/lexers/LexNsis.cxx
 variableScope:lexilla/lexers/LexOpal.cxx
+constParameterReference:lexilla/lexers/LexOpal.cxx
 knownConditionTrueFalse:lexilla/lexers/LexOpal.cxx
 constParameterReference:lexilla/lexers/LexOScript.cxx
+constParameterReference:lexilla/lexers/LexPascal.cxx
 variableScope:lexilla/lexers/LexPB.cxx
 constParameterReference:lexilla/lexers/LexPerl.cxx
+constVariableReference:lexilla/lexers/LexPerl.cxx
 knownConditionTrueFalse:lexilla/lexers/LexPerl.cxx
+constParameterReference:lexilla/lexers/LexPLM.cxx
 constParameterReference:lexilla/lexers/LexPO.cxx
 constParameterReference:lexilla/lexers/LexPython.cxx
 shadowVariable:lexilla/lexers/LexPowerPro.cxx
 knownConditionTrueFalse:lexilla/lexers/LexPowerPro.cxx
 variableScope:lexilla/lexers/LexProgress.cxx
+constParameterReference:lexilla/lexers/LexProgress.cxx
 constParameterReference:lexilla/lexers/LexRaku.cxx
 variableScope:lexilla/lexers/LexRaku.cxx
 redundantInitialization:lexilla/lexers/LexRegistry.cxx
@@ -128,10 +146,14 @@ constParameterReference:lexilla/lexers/LexRust.cxx
 knownConditionTrueFalse:lexilla/lexers/LexScriptol.cxx
 variableScope:lexilla/lexers/LexSpecman.cxx
 unreadVariable:lexilla/lexers/LexSpice.cxx
+constParameterReference:lexilla/lexers/LexSpice.cxx
 constParameterReference:lexilla/lexers/LexSTTXT.cxx
+constParameterReference:lexilla/lexers/LexTACL.cxx
 knownConditionTrueFalse:lexilla/lexers/LexTACL.cxx
 clarifyCalculation:lexilla/lexers/LexTADS3.cxx
 constParameterReference:lexilla/lexers/LexTADS3.cxx
+constParameterReference:lexilla/lexers/LexTAL.cxx
+constVariableReference:lexilla/lexers/LexTCL.cxx
 invalidscanf:lexilla/lexers/LexTCMD.cxx
 constParameterReference:lexilla/lexers/LexTeX.cxx
 variableScope:lexilla/lexers/LexTeX.cxx
@@ -149,6 +171,7 @@ variableScope:lexilla/lexers/LexVHDL.cxx
 unreadVariable:lexilla/lexers/LexVisualProlog.cxx
 variableScope:lexilla/lexers/LexVisualProlog.cxx
 shiftTooManyBitsSigned:lexilla/lexers/LexVisualProlog.cxx
+iterateByValue:lexilla/lexers/LexVisualProlog.cxx
 unreadVariable:lexilla/lexers/LexX12.cxx
 constVariableReference:lexilla/lexers/LexX12.cxx
 constParameterPointer:lexilla/lexers/LexX12.cxx
@@ -165,6 +188,7 @@ constParameterCallback:lexilla/lexers/LexPython.cxx
 constParameterCallback:lexilla/lexers/LexScriptol.cxx
 constParameterCallback:lexilla/lexers/LexVB.cxx
 
+constVariableReference:lexilla/lexers/LexBibTeX.cxx
 constVariableReference:lexilla/lexers/LexCSS.cxx
 constVariableReference:lexilla/lexers/LexCrontab.cxx
 constVariableReference:lexilla/lexers/LexGui4Cli.cxx
diff --git a/lexilla/doc/Lexilla.html b/lexilla/doc/Lexilla.html
index 1ae9bf270..8c8694f02 100644
--- a/lexilla/doc/Lexilla.html
+++ b/lexilla/doc/Lexilla.html
@@ -9,7 +9,7 @@
     <meta name="keywords" content="Scintilla, SciTE, Editing Component, Text Editor" />
     <meta name="Description"
     content="www.scintilla.org is the home of the Scintilla editing component and SciTE text editor application." />
-    <meta name="Date.Modified" content="20231227" />
+    <meta name="Date.Modified" content="20240305" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
     <style type="text/css">
         .logo {
@@ -61,8 +61,8 @@
           <font color="#FFCC99" size="4"> A library of language lexers for use with Scintilla</font>
         </td>
         <td width="40%" align="right">
-          <font color="#FFCC99" size="3">Release version 5.3.0<br />
-           Site last modified December 27 2023</font>
+          <font color="#FFCC99" size="3">Release version 5.3.1<br />
+           Site last modified March 5 2024</font>
         </td>
         <td width="20%">
           &nbsp;
@@ -77,11 +77,11 @@
       </tr>
     </table>
     <ul id="versionlist">
+      <li>Version 5.3.1 improves Assembler, Bash, Batch, JavaScript, Python, and Ruby.</li>
       <li>Version 5.3.0 improves Bash, HTML, and Lua.</li>
       <li>Version 5.2.9 fixes potential problems on macOS 12 and older when built with Xcode 15.0.</li>
       <li>Version 5.2.8 improves Python and R.</li>
       <li>Version 5.2.7 improves Bash, F#, and HTML.</li>
-      <li>Version 5.2.6 improves Bash, Errorlist, HTML, Matlab, and Visual Prolog.</li>
     </ul>
     <ul id="menu">
       <li id="remote1"><a href="https://www.scintilla.org/SciTEImage.html">Screenshot</a></li>
diff --git a/lexilla/doc/LexillaDownload.html b/lexilla/doc/LexillaDownload.html
index a6f86cb02..af2c8c356 100644
--- a/lexilla/doc/LexillaDownload.html
+++ b/lexilla/doc/LexillaDownload.html
@@ -26,9 +26,9 @@
     <table bgcolor="#CCCCCC" width="100%" cellspacing="0" cellpadding="8" border="0">
       <tr>
         <td>
-          <font size="4"> <a href="https://www.scintilla.org/lexilla530.zip">
+          <font size="4"> <a href="https://www.scintilla.org/lexilla531.zip">
 	Windows</a>&nbsp;&nbsp;
-	<a href="https://www.scintilla.org/lexilla530.tgz">
+	<a href="https://www.scintilla.org/lexilla531.tgz">
           GTK/Linux</a>&nbsp;&nbsp;
 	</font>
         </td>
@@ -42,7 +42,7 @@
       containing very few restrictions.
     </p>
     <h3>
-       Release 5.3.0
+       Release 5.3.1
     </h3>
     <h4>
        Source Code
@@ -50,8 +50,8 @@
        The source code package contains all of the source code for Lexilla but no binary
 	executable code and is available in
        <ul>
-       <li><a href="https://www.scintilla.org/lexilla530.zip">zip format</a> (1.3M) commonly used on Windows</li>
-       <li><a href="https://www.scintilla.org/lexilla530.tgz">tgz format</a> (0.9M) commonly used on Linux and compatible operating systems</li>
+       <li><a href="https://www.scintilla.org/lexilla531.zip">zip format</a> (1.3M) commonly used on Windows</li>
+       <li><a href="https://www.scintilla.org/lexilla531.tgz">tgz format</a> (0.9M) commonly used on Linux and compatible operating systems</li>
        </ul>
        Instructions for building on both Windows and Linux are included in the readme file.
     <h4>
diff --git a/lexilla/doc/LexillaHistory.html b/lexilla/doc/LexillaHistory.html
index cfbc8097e..9c8ba5625 100644
--- a/lexilla/doc/LexillaHistory.html
+++ b/lexilla/doc/LexillaHistory.html
@@ -584,9 +584,43 @@
 	<td>German Aizek</td>
 	<td>Tsuyoshi Miyake</td>
 	<td>Martin Schäfer</td>
+	<td>RainRat</td>
     </tr>
     </table>
     <h2>Releases</h2>
+    <h3>
+       <a href="https://www.scintilla.org/lexilla531.zip">Release 5.3.1</a>
+    </h3>
+    <ul>
+	<li>
+	Released 5 March 2024.
+	</li>
+	<li>
+	Assembler: After comments, treat \r\n line ends the same as \n. This makes testing easier.
+	</li>
+	<li>
+	Bash: Fix folding when line changed to/from comment and previous line is comment.
+	<a href="https://github.com/ScintillaOrg/lexilla/issues/224">Issue #224</a>.
+	</li>
+	<li>
+	Batch: Fix handling ':' next to keywords.
+	<a href="https://github.com/ScintillaOrg/lexilla/issues/222">Issue #222</a>.
+	</li>
+	<li>
+	JavaScript: in cpp lexer, add lexer.cpp.backquoted.strings=2 mode to treat ` back-quoted
+	strings as template literals which allow embedded ${expressions}.
+	<a href="https://github.com/ScintillaOrg/lexilla/issues/94">Issue #94</a>.
+	</li>
+	<li>
+	Python: fix lexing of rb'' and rf'' strings.
+	<a href="https://github.com/ScintillaOrg/lexilla/issues/223">Issue #223</a>,
+	<a href="https://github.com/ScintillaOrg/lexilla/pull/227">Pull request #227</a>.
+	</li>
+	<li>
+	Ruby: fix lexing of methods on numeric literals like '3.times' so the '.' and method name do not appear in numeric style.
+	<a href="https://github.com/ScintillaOrg/lexilla/issues/225">Issue #225</a>.
+	</li>
+    </ul>
     <h3>
        <a href="https://www.scintilla.org/lexilla530.zip">Release 5.3.0</a>
     </h3>
@@ -1964,7 +1998,7 @@
 	</li>
 	<li>
 	Add SCI_SETTABMINIMUMWIDTH to set the minimum width of tabs.
-	This allows minimaps or overviews to be layed out to match the full size editing view.
+	This allows minimaps or overviews to be laid out to match the full size editing view.
 	<a href="https://sourceforge.net/p/scintilla/bugs/2118/">Bug #2118</a>.
 	</li>
 	<li>
@@ -2533,7 +2567,7 @@
 	<a href="https://sourceforge.net/p/scintilla/feature-requests/1210/">Feature #1210.</a>
 	</li>
 	<li>
-	Fix hang in Lua lexer when lexing a label upto the terminating "::".
+	Fix hang in Lua lexer when lexing a label up to the terminating "::".
 	<a href="https://sourceforge.net/p/scintilla/bugs/1999/">Bug #1999</a>.
 	</li>
 	<li>
@@ -2760,7 +2794,7 @@
 	'Ctrl+L|SCI_LINEDELETE|'.
 	</li>
 	<li>
-	The Matlab lexer treats 'end' as a number rather than a keyword when used as a index.
+	The Matlab lexer treats 'end' as a number rather than a keyword when used as an index.
 	This also stops incorrect folding.
 	<a href="https://sourceforge.net/p/scintilla/bugs/1951/">Bug #1951</a>.
 	</li>
@@ -9803,7 +9837,7 @@
 	SciTE crashing bug fixed in incremental search on Windows ME.
 	</li>
 	<li>
-	SciTE on Windows has a optional find and replace dialogs that can search through
+	SciTE on Windows has an optional find and replace dialogs that can search through
 	all buffers and search within a particular style number.
 	</li>
     </ul>
@@ -11372,7 +11406,7 @@
 	SciTE's Export as LaTeX output improved.
       </li>
       <li>
-	Better choice of autocompletion displaying above the caret rather then
+	Better choice of autocompletion displaying above the caret rather than
 	below when that is more sensible.
       </li>
       <li>
@@ -13957,7 +13991,7 @@
       <li>
         Scintilla supports a 'savepoint' in the undo stack which can be set by the container when
         the document is saved. Notifications are sent to the container when the savepoint is
-        entered or left, allowing the container to to display a dirty indicator and change its
+        entered or left, allowing the container to display a dirty indicator and change its
         menus.
       </li>
       <li>
diff --git a/lexilla/lexers/LexAsm.cxx b/lexilla/lexers/LexAsm.cxx
index 44f399a26..7e7ab3c32 100644
--- a/lexilla/lexers/LexAsm.cxx
+++ b/lexilla/lexers/LexAsm.cxx
@@ -265,11 +265,19 @@ void SCI_METHOD LexerAsm::Lex(Sci_PositionU startPos, Sci_Position length, int i
 	for (; sc.More(); sc.Forward())
 	{
 
-		// Prevent SCE_ASM_STRINGEOL from leaking back to previous line
-		if (sc.atLineStart && (sc.state == SCE_ASM_STRING)) {
-			sc.SetState(SCE_ASM_STRING);
-		} else if (sc.atLineStart && (sc.state == SCE_ASM_CHARACTER)) {
-			sc.SetState(SCE_ASM_CHARACTER);
+		if (sc.atLineStart) {
+			switch (sc.state) {
+			case SCE_ASM_STRING:
+			case SCE_ASM_CHARACTER:
+				// Prevent SCE_ASM_STRINGEOL from leaking back to previous line
+				sc.SetState(sc.state);
+				break;
+			case SCE_ASM_COMMENT:
+				sc.SetState(SCE_ASM_DEFAULT);
+				break;
+			default:
+				break;
+			}
 		}
 
 		// Handle line continuation generically.
@@ -326,15 +334,11 @@ void SCI_METHOD LexerAsm::Lex(Sci_PositionU startPos, Sci_Position length, int i
 		} else if (sc.state == SCE_ASM_COMMENTDIRECTIVE) {
 			char delimiter = options.delimiter.empty() ? '~' : options.delimiter.c_str()[0];
 			if (sc.ch == delimiter) {
-				while (!sc.atLineEnd) {
+				while (!sc.MatchLineEnd()) {
 					sc.Forward();
 				}
 				sc.SetState(SCE_ASM_DEFAULT);
 			}
-		} else if (sc.state == SCE_ASM_COMMENT ) {
-			if (sc.atLineEnd) {
-				sc.SetState(SCE_ASM_DEFAULT);
-			}
 		} else if (sc.state == SCE_ASM_STRING) {
 			if (sc.ch == '\\') {
 				if (sc.chNext == '\"' || sc.chNext == '\'' || sc.chNext == '\\') {
diff --git a/lexilla/lexers/LexBash.cxx b/lexilla/lexers/LexBash.cxx
index 8bae51697..e44fdbf2d 100644
--- a/lexilla/lexers/LexBash.cxx
+++ b/lexilla/lexers/LexBash.cxx
@@ -16,6 +16,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <initializer_list>
 #include <functional>
 
 #include "ILexer.h"
@@ -23,6 +24,7 @@
 #include "SciLexer.h"
 
 #include "StringCopy.h"
+#include "InList.h"
 #include "WordList.h"
 #include "LexAccessor.h"
 #include "StyleContext.h"
@@ -63,7 +65,7 @@ enum class CmdState {
 	Delimiter,
 };
 
-enum class CommandSubstitution {
+enum class CommandSubstitution : int {
 	Backtick,
 	Inside,
 	InsideTrack,
@@ -181,7 +183,7 @@ struct OptionsBash {
 	bool stylingInsideParameter = false;
 	bool stylingInsideHeredoc = false;
 	bool nestedBackticks = true;
-	int commandSubstitution = static_cast<int>(CommandSubstitution::Backtick);
+	CommandSubstitution commandSubstitution = CommandSubstitution::Backtick;
 	std::string specialParameter = BASH_SPECIAL_PARAMETER;
 
 	[[nodiscard]] bool stylingInside(int state) const noexcept {
@@ -622,7 +624,7 @@ void SCI_METHOD LexerBash::Lex(Sci_PositionU startPos, Sci_Position length, int
 
 	QuoteStackCls QuoteStack(setParamStart);
 	QuoteStack.nestedBackticks = options.nestedBackticks;
-	QuoteStack.commandSubstitution = static_cast<CommandSubstitution>(options.commandSubstitution);
+	QuoteStack.commandSubstitution = options.commandSubstitution;
 
 	const WordClassifier &classifierIdentifiers = subStyles.Classifier(SCE_SH_IDENTIFIER);
 	const WordClassifier &classifierScalars = subStyles.Classifier(SCE_SH_SCALAR);
@@ -1187,10 +1189,17 @@ void SCI_METHOD LexerBash::Fold(Sci_PositionU startPos_, Sci_Position length, in
 
 	LexAccessor styler(pAccess);
 
-	const Sci_Position startPos = startPos_;
+	Sci_Position startPos = startPos_;
 	const Sci_Position endPos = startPos + length;
 	int visibleChars = 0;
 	Sci_Position lineCurrent = styler.GetLine(startPos);
+	// Backtrack to previous line in case need to fix its fold status
+	if (lineCurrent > 0) {
+		lineCurrent--;
+		startPos = styler.LineStart(lineCurrent);
+		initStyle = (startPos > 0) ? styler.StyleIndexAt(startPos - 1) : 0;
+	}
+
 	int levelPrev = styler.LevelAt(lineCurrent) & SC_FOLDLEVELNUMBERMASK;
 	int levelCurrent = levelPrev;
 	char chNext = styler[startPos];
@@ -1215,28 +1224,32 @@ void SCI_METHOD LexerBash::Fold(Sci_PositionU startPos_, Sci_Position length, in
 					 && !IsCommentLine(lineCurrent + 1, styler))
 				levelCurrent--;
 		}
-		if (style == SCE_SH_WORD) {
+
+		switch (style) {
+		case SCE_SH_WORD:
 			if ((wordlen + 1) < sizeof(word))
 				word[wordlen++] = ch;
 			if (styleNext != style) {
 				word[wordlen] = '\0';
 				wordlen = 0;
-				if (strcmp(word, "if") == 0 || strcmp(word, "case") == 0 || strcmp(word, "do") == 0) {
+				if (InList(word, {"if", "case", "do"})) {
 					levelCurrent++;
-				} else if (strcmp(word, "fi") == 0 || strcmp(word, "esac") == 0 || strcmp(word, "done") == 0) {
+				} else if (InList(word, {"fi", "esac", "done"})) {
 					levelCurrent--;
 				}
 			}
-		}
-		if (style == SCE_SH_OPERATOR) {
+			break;
+
+		case SCE_SH_OPERATOR:
 			if (ch == '{') {
 				levelCurrent++;
 			} else if (ch == '}') {
 				levelCurrent--;
 			}
-		}
+			break;
+
 		// Here Document folding
-		if (style == SCE_SH_HERE_DELIM) {
+		case SCE_SH_HERE_DELIM:
 			if (stylePrev == SCE_SH_HERE_Q) {
 				levelCurrent--;
 			} else if (stylePrev != SCE_SH_HERE_DELIM) {
@@ -1246,9 +1259,14 @@ void SCI_METHOD LexerBash::Fold(Sci_PositionU startPos_, Sci_Position length, in
 					}
 				}
 			}
-		} else if (style == SCE_SH_HERE_Q && styleNext == SCE_SH_DEFAULT) {
-			levelCurrent--;
+			break;
+		case SCE_SH_HERE_Q:
+			if (styleNext == SCE_SH_DEFAULT) {
+				levelCurrent--;
+			}
+			break;
 		}
+
 		if (atEOL) {
 			int lev = levelPrev;
 			if (visibleChars == 0 && options.foldCompact)
diff --git a/lexilla/lexers/LexBatch.cxx b/lexilla/lexers/LexBatch.cxx
index 225465cf0..9053fb0a0 100644
--- a/lexilla/lexers/LexBatch.cxx
+++ b/lexilla/lexers/LexBatch.cxx
@@ -14,11 +14,13 @@
 
 #include <string>
 #include <string_view>
+#include <initializer_list>
 
 #include "ILexer.h"
 #include "Scintilla.h"
 #include "SciLexer.h"
 
+#include "InList.h"
 #include "WordList.h"
 #include "LexAccessor.h"
 #include "Accessor.h"
@@ -200,18 +202,19 @@ void ColouriseBatchDoc(
 					styler.ColourTo(startLine + offset - 1, SCE_BAT_DEFAULT);
 				}
 				char wordBuffer[81]{};		// Word Buffer - large to catch long paths
-				// Copy word from Line Buffer into Word Buffer
+				// Copy word from Line Buffer into Word Buffer and convert to lower case
 				Sci_PositionU wbl = 0;		// Word Buffer Length
 				for (; offset < lengthLine && wbl < 80 &&
 						!isspacechar(lineBuffer[offset]); wbl++, offset++) {
-					wordBuffer[wbl] = tolower(lineBuffer[offset]);
+					wordBuffer[wbl] = MakeLowerCase(lineBuffer[offset]);
 				}
 				wordBuffer[wbl] = '\0';
+				const std::string_view wordView(wordBuffer);
 				Sci_PositionU wbo = 0;		// Word Buffer Offset - also Special Keyword Buffer Length
 
 				// Check for Comment - return if found
 				if (continueProcessing) {
-					if ((CompareCaseInsensitive(wordBuffer, "rem") == 0) || (wordBuffer[0] == ':' && wordBuffer[1] == ':')) {
+					if ((wordView == "rem") || (wordBuffer[0] == ':' && wordBuffer[1] == ':')) {
 						if ((offset == wbl) || !textQuoted(lineBuffer, offset - wbl)) {
 							styler.ColourTo(startLine + offset - wbl - 1, SCE_BAT_DEFAULT);
 							styler.ColourTo(endPos, SCE_BAT_COMMENT);
@@ -248,19 +251,16 @@ void ColouriseBatchDoc(
 				} else if ((keywords.InList(wordBuffer)) &&
 					(continueProcessing)) {
 					// ECHO, GOTO, PROMPT and SET require no further Regular Keyword Checking
-					if ((CompareCaseInsensitive(wordBuffer, "echo") == 0) ||
-						(CompareCaseInsensitive(wordBuffer, "goto") == 0) ||
-						(CompareCaseInsensitive(wordBuffer, "prompt") == 0)) {
+					if (InList(wordView, {"echo", "goto", "prompt"})) {
 						continueProcessing = false;
 					}
 					// SET requires additional processing for the assignment operator
-					if (CompareCaseInsensitive(wordBuffer, "set") == 0) {
+					if (wordView == "set") {
 						continueProcessing = false;
 						isNotAssigned=true;
 					}
 					// Identify External Command / Program Location for ERRORLEVEL, and EXIST
-					if ((CompareCaseInsensitive(wordBuffer, "errorlevel") == 0) ||
-						(CompareCaseInsensitive(wordBuffer, "exist") == 0)) {
+					if (InList(wordView, {"errorlevel", "exist"})) {
 						// Reset External Command / Program Location
 						cmdLoc = offset;
 						// Skip next spaces
@@ -279,10 +279,7 @@ void ColouriseBatchDoc(
 							cmdLoc++;
 						}
 					// Identify External Command / Program Location for CALL, DO, LOADHIGH and LH
-					} else if ((CompareCaseInsensitive(wordBuffer, "call") == 0) ||
-						(CompareCaseInsensitive(wordBuffer, "do") == 0) ||
-						(CompareCaseInsensitive(wordBuffer, "loadhigh") == 0) ||
-						(CompareCaseInsensitive(wordBuffer, "lh") == 0)) {
+					} else if (InList(wordView, {"call", "do", "loadhigh", "lh"})) {
 						// Reset External Command / Program Location
 						cmdLoc = offset;
 						// Skip next spaces
@@ -290,6 +287,11 @@ void ColouriseBatchDoc(
 							(isspacechar(lineBuffer[cmdLoc]))) {
 							cmdLoc++;
 						}
+						// Check if call is followed by a label
+						if ((lineBuffer[cmdLoc] == ':') &&
+							(wordView == "call")) {
+							continueProcessing = false;
+						}
 					}
 					// Colorize Regular keyword
 					styler.ColourTo(startLine + offset - 1, SCE_BAT_WORD);
@@ -317,10 +319,12 @@ void ColouriseBatchDoc(
 						// Check for Special Keyword in list
 						if ((keywords.InList(sKeywordBuffer)) &&
 							((IsBOperator(wordBuffer[wbo])) ||
-							(IsBSeparator(wordBuffer[wbo])))) {
+							(IsBSeparator(wordBuffer[wbo])) ||
+							(wordBuffer[wbo] == ':' &&
+							(InList(sKeywordBuffer, {"call", "echo", "goto"}) )))) {
 							sKeywordFound = true;
 							// ECHO requires no further Regular Keyword Checking
-							if (CompareCaseInsensitive(sKeywordBuffer, "echo") == 0) {
+							if (std::string_view(sKeywordBuffer) == "echo") {
 								continueProcessing = false;
 							}
 							// Colorize Special Keyword as Regular Keyword
@@ -347,11 +351,11 @@ void ColouriseBatchDoc(
 							// Reset Offset to re-process remainder of word
 							offset -= (wbl - wbo);
 							// CHOICE requires no further Regular Keyword Checking
-							if (CompareCaseInsensitive(wordBuffer, "choice") == 0) {
+							if (wordView == "choice") {
 								continueProcessing = false;
 							}
 							// Check for START (and its switches) - What follows is External Command \ Program
-							if (CompareCaseInsensitive(wordBuffer, "start") == 0) {
+							if (wordView == "start") {
 								// Reset External Command / Program Location
 								cmdLoc = offset;
 								// Skip next spaces
@@ -576,7 +580,7 @@ void ColouriseBatchDoc(
 							isNotAssigned=false;
 						}
 						// Colorize Other Operators
-						// Do not Colorize Paranthesis, quoted text and escaped operators
+						// Do not Colorize Parenthesis, quoted text and escaped operators
 						if (((wordBuffer[0] != ')') && (wordBuffer[0] != '(')
 						&& !textQuoted(lineBuffer, offset - wbl)  && !IsEscaped(lineBuffer,offset - wbl + wbo))
 						&& !((wordBuffer[0] == '=') && !isNotAssigned ))
diff --git a/lexilla/lexers/LexCPP.cxx b/lexilla/lexers/LexCPP.cxx
index 00494cd28..692b98ce7 100644
--- a/lexilla/lexers/LexCPP.cxx
+++ b/lexilla/lexers/LexCPP.cxx
@@ -167,9 +167,11 @@ class EscapeSequence {
 	const CharacterSet *escapeSetValid = nullptr;
 	int digitsLeft = 0;
 public:
+	int outerState = SCE_C_DEFAULT;
 	EscapeSequence() = default;
-	void resetEscapeState(int nextChar) noexcept {
+	void resetEscapeState(int state, int nextChar) noexcept {
 		digitsLeft = 0;
+		outerState = state;
 		escapeSetValid = &setNoneNumeric;
 		if (nextChar == 'U') {
 			digitsLeft = 9;
@@ -185,7 +187,7 @@ public:
 			escapeSetValid = &setOctDigits;
 		}
 	}
-	bool atEscapeEnd(int currChar) const noexcept {
+	[[nodiscard]] bool atEscapeEnd(int currChar) const noexcept {
 		return (digitsLeft <= 0) || !escapeSetValid->Contains(currChar);
 	}
 	void consumeDigit() noexcept {
@@ -254,28 +256,27 @@ class LinePPState {
 	// level is the nesting level of #if constructs
 	int level = -1;
 	static const int maximumNestingLevel = 31;
-	int maskLevel() const noexcept {
+	[[nodiscard]] int maskLevel() const noexcept {
 		if (level >= 0) {
 			return 1 << level;
-		} else {
-			return 1;
 		}
+		return 1;
 	}
 public:
 	LinePPState() noexcept = default;
-	bool ValidLevel() const noexcept {
+	[[nodiscard]] bool ValidLevel() const noexcept {
 		return level >= 0 && level < maximumNestingLevel;
 	}
-	bool IsActive() const noexcept {
+	[[nodiscard]] bool IsActive() const noexcept {
 		return state == 0;
 	}
-	bool IsInactive() const noexcept {
+	[[nodiscard]] bool IsInactive() const noexcept {
 		return state != 0;
 	}
-	int ActiveState() const noexcept {
+	[[nodiscard]] int ActiveState() const noexcept {
 		return state ? inactiveFlag : 0;
 	}
-	bool CurrentIfTaken() const noexcept {
+	[[nodiscard]] bool CurrentIfTaken() const noexcept {
 		return (ifTaken & maskLevel()) != 0;
 	}
 	void StartSection(bool on) noexcept {
@@ -310,7 +311,7 @@ public:
 class PPStates {
 	std::vector<LinePPState> vlls;
 public:
-	LinePPState ForLine(Sci_Position line) const noexcept {
+	[[nodiscard]] LinePPState ForLine(Sci_Position line) const noexcept {
 		if ((line > 0) && (vlls.size() > static_cast<size_t>(line))) {
 			return vlls[line];
 		}
@@ -322,6 +323,18 @@ public:
 	}
 };
 
+enum class BackQuotedString : int {
+	None,
+	RawString,
+	TemplateLiteral,
+};
+
+// string interpolating state
+struct InterpolatingState {
+	int state;
+	int braceCount;
+};
+
 // An individual named option for use in an OptionSet
 
 // Options used for LexerCPP
@@ -333,7 +346,7 @@ struct OptionsCPP {
 	bool verbatimStringsAllowEscapes = false;
 	bool triplequotedStrings = false;
 	bool hashquotedStrings = false;
-	bool backQuotedStrings = false;
+	BackQuotedString backQuotedStrings = BackQuotedString::None;
 	bool escapeSequence = false;
 	bool fold = false;
 	bool foldSyntaxBased = true;
@@ -385,7 +398,10 @@ struct OptionSetCPP : public OptionSet<OptionsCPP> {
 			"Set to 1 to enable highlighting of hash-quoted strings.");
 
 		DefineProperty("lexer.cpp.backquoted.strings", &OptionsCPP::backQuotedStrings,
-			"Set to 1 to enable highlighting of back-quoted raw strings .");
+			"Set how to highlighting back-quoted strings. "
+			"0 (the default) no highlighting. "
+			"1 highlighted as Go raw string. "
+			"2 highlighted as JavaScript template literal.");
 
 		DefineProperty("lexer.cpp.escape.sequence", &OptionsCPP::escapeSequence,
 			"Set to 1 to enable highlighting of escape sequences in strings");
@@ -480,6 +496,7 @@ class LexerCPP : public ILexer5 {
 	CharacterSet setWordStart;
 	PPStates vlls;
 	std::vector<PPDefinition> ppDefineHistory;
+	std::map<Sci_Position, std::vector<InterpolatingState>> interpolatingAtEol;
 	WordList keywords;
 	WordList keywords2;
 	WordList keywords3;
@@ -497,11 +514,11 @@ class LexerCPP : public ILexer5 {
 			arguments.clear();
 			return *this;
 		}
-		bool IsMacro() const noexcept {
+		[[nodiscard]] bool IsMacro() const noexcept {
 			return !arguments.empty();
 		}
 	};
-	typedef std::map<std::string, SymbolValue> SymbolTable;
+	using SymbolTable = std::map<std::string, SymbolValue>;
 	SymbolTable preprocessorDefinitionsStart;
 	OptionsCPP options;
 	OptionSetCPP osCPP;
@@ -526,8 +543,7 @@ public:
 	LexerCPP(LexerCPP &&) = delete;
 	void operator=(const LexerCPP &) = delete;
 	void operator=(LexerCPP &&) = delete;
-	virtual ~LexerCPP() {
-	}
+	virtual ~LexerCPP() = default;
 	void SCI_METHOD Release() noexcept override {
 		delete this;
 	}
@@ -661,7 +677,7 @@ public:
 		return style & ~inactiveFlag;
 	}
 	void EvaluateTokens(Tokens &tokens, const SymbolTable &preprocessorDefinitions);
-	Tokens Tokenize(const std::string &expr) const;
+	[[nodiscard]] Tokens Tokenize(const std::string &expr) const;
 	bool EvaluateExpression(const std::string &expr, const SymbolTable &preprocessorDefinitions);
 };
 
@@ -718,21 +734,19 @@ Sci_Position SCI_METHOD LexerCPP::WordListSet(int n, const char *wl) {
 					const char *cpEquals = strchr(cpDefinition, '=');
 					if (cpEquals) {
 						std::string name(cpDefinition, cpEquals - cpDefinition);
-						std::string val(cpEquals+1);
+						const std::string val(cpEquals+1);
 						const size_t bracket = name.find('(');
 						const size_t bracketEnd = name.find(')');
 						if ((bracket != std::string::npos) && (bracketEnd != std::string::npos)) {
 							// Macro
-							std::string args = name.substr(bracket + 1, bracketEnd - bracket - 1);
+							const std::string args = name.substr(bracket + 1, bracketEnd - bracket - 1);
 							name = name.substr(0, bracket);
 							preprocessorDefinitionsStart[name] = SymbolValue(val, args);
 						} else {
 							preprocessorDefinitionsStart[name] = val;
 						}
 					} else {
-						std::string name(cpDefinition);
-						std::string val("1");
-						preprocessorDefinitionsStart[name] = val;
+						preprocessorDefinitionsStart[std::string(cpDefinition)] = std::string("1");
 					}
 				}
 			}
@@ -771,7 +785,21 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 	bool inRERange = false;
 	bool seenDocKeyBrace = false;
 
+	std::vector<InterpolatingState> interpolatingStack;
+
 	Sci_Position lineCurrent = styler.GetLine(startPos);
+	if (options.backQuotedStrings == BackQuotedString::TemplateLiteral) {
+		// code copied from LexPython
+		auto it = interpolatingAtEol.find(lineCurrent - 1);
+		if (it != interpolatingAtEol.end()) {
+			interpolatingStack = it->second;
+		}
+		it = interpolatingAtEol.lower_bound(lineCurrent);
+		if (it != interpolatingAtEol.end()) {
+			interpolatingAtEol.erase(it, interpolatingAtEol.end());
+		}
+	}
+
 	if ((MaskActive(initStyle) == SCE_C_PREPROCESSOR) ||
       (MaskActive(initStyle) == SCE_C_COMMENTLINE) ||
       (MaskActive(initStyle) == SCE_C_COMMENTLINEDOC)) {
@@ -864,6 +892,9 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 			if (!rawStringTerminator.empty()) {
 				rawSTNew.Set(lineCurrent-1, rawStringTerminator);
 			}
+			if (!interpolatingStack.empty()) {
+				interpolatingAtEol[sc.currentLine] = interpolatingStack;
+			}
 		}
 
 		// Handle line continuation generically.
@@ -1051,7 +1082,7 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 					} else {
 						sc.GetCurrentString(currentText, transform);
 						assert(!currentText.empty());
-						std::string currentSuffix = currentText.substr(1);
+						const std::string currentSuffix = currentText.substr(1);
 						if (!keywords3.InList(currentSuffix) && !keywords3.InList(currentText)) {
 							const int subStyleCDKW = classifierDocKeyWords.ValueFor(currentSuffix);
 							if (subStyleCDKW >= 0) {
@@ -1087,8 +1118,8 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 					}
 				} else if (sc.ch == '\\') {
 					if (options.escapeSequence) {
+						escapeSeq.resetEscapeState(sc.state, sc.chNext);
 						sc.SetState(SCE_C_ESCAPESEQUENCE|activitySet);
-						escapeSeq.resetEscapeState(sc.chNext);
 					}
 					sc.Forward(); // Skip all characters after the backslash
 				} else if (sc.ch == '\"') {
@@ -1101,20 +1132,9 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 				break;
 			case SCE_C_ESCAPESEQUENCE:
 				escapeSeq.consumeDigit();
-				if (!escapeSeq.atEscapeEnd(sc.ch)) {
-					break;
-				}
-				if (sc.ch == '"') {
-					sc.SetState(SCE_C_STRING|activitySet);
-					sc.ForwardSetState(SCE_C_DEFAULT|activitySet);
-				} else if (sc.ch == '\\') {
-					escapeSeq.resetEscapeState(sc.chNext);
-					sc.Forward();
-				} else {
-					sc.SetState(SCE_C_STRING|activitySet);
-					if (sc.atLineEnd) {
-						sc.ChangeState(SCE_C_STRINGEOL|activitySet);
-					}
+				if (escapeSeq.atEscapeEnd(sc.ch)) {
+					sc.SetState(escapeSeq.outerState);
+					continue;
 				}
 				break;
 			case SCE_C_HASHQUOTEDSTRING:
@@ -1131,7 +1151,21 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 					for (size_t termPos=rawStringTerminator.size(); termPos; termPos--)
 						sc.Forward();
 					sc.SetState(SCE_C_DEFAULT|activitySet);
-					rawStringTerminator.clear();
+					if (interpolatingStack.empty()) {
+						rawStringTerminator.clear();
+					}
+				} else if (options.backQuotedStrings == BackQuotedString::TemplateLiteral) {
+					if (sc.ch == '\\') {
+						if (options.escapeSequence) {
+							escapeSeq.resetEscapeState(sc.state, sc.chNext);
+							sc.SetState(SCE_C_ESCAPESEQUENCE|activitySet);
+						}
+						sc.Forward(); // Skip all characters after the backslash
+					} else if (sc.Match('$', '{')) {
+						interpolatingStack.push_back({sc.state, 1});
+						sc.SetState(SCE_C_OPERATOR|activitySet);
+						sc.Forward();
+					}
 				}
 				break;
 			case SCE_C_CHARACTER:
@@ -1222,7 +1256,7 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 			} else if (options.hashquotedStrings && sc.Match('#', '\"')) {
 				sc.SetState(SCE_C_HASHQUOTEDSTRING|activitySet);
 				sc.Forward();
-			} else if (options.backQuotedStrings && sc.Match('`')) {
+			} else if ((options.backQuotedStrings != BackQuotedString::None) && sc.Match('`')) {
 				sc.SetState(SCE_C_STRINGRAW|activitySet);
 				rawStringTerminator = "`";
 			} else if (IsADigit(sc.ch) || (sc.ch == '.' && IsADigit(sc.chNext))) {
@@ -1336,7 +1370,7 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 									// Inactive, if expression true then may become active if parent scope active
 									assert(sc.state == (SCE_C_PREPROCESSOR | inactiveFlag));
 									// Similar to #if
-									std::string restOfLine = GetRestOfLine(styler, sc.currentPos + 4, true);
+									const std::string restOfLine = GetRestOfLine(styler, sc.currentPos + 4, true);
 									const bool ifGood = EvaluateExpression(restOfLine, preprocessorDefinitions);
 									if (ifGood) {
 										preproc.InvertCurrentLevel();
@@ -1365,13 +1399,13 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 								size_t endName = startName;
 								while ((endName < restOfLine.length()) && setWord.Contains(restOfLine[endName]))
 									endName++;
-								std::string key = restOfLine.substr(startName, endName-startName);
+								const std::string key = restOfLine.substr(startName, endName-startName);
 								if ((endName < restOfLine.length()) && (restOfLine.at(endName) == '(')) {
 									// Macro
 									size_t endArgs = endName;
 									while ((endArgs < restOfLine.length()) && (restOfLine[endArgs] != ')'))
 										endArgs++;
-									std::string args = restOfLine.substr(endName + 1, endArgs - endName - 1);
+									const std::string args = restOfLine.substr(endName + 1, endArgs - endName - 1);
 									size_t startValue = endArgs+1;
 									while ((startValue < restOfLine.length()) && IsSpaceOrTab(restOfLine[startValue]))
 										startValue++;
@@ -1410,6 +1444,19 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 				}
 			} else if (isoperator(sc.ch)) {
 				sc.SetState(SCE_C_OPERATOR|activitySet);
+				if (!interpolatingStack.empty() && AnyOf(sc.ch, '{', '}')) {
+					InterpolatingState &current = interpolatingStack.back();
+					if (sc.ch == '{') {
+						current.braceCount += 1;
+					} else {
+						current.braceCount -= 1;
+						if (current.braceCount == 0) {
+							sc.ForwardSetState(current.state);
+							interpolatingStack.pop_back();
+							continue;
+						}
+					}
+				}
 			}
 		}
 
diff --git a/lexilla/lexers/LexErrorList.cxx b/lexilla/lexers/LexErrorList.cxx
index 1e2b75de4..acdbfeb48 100644
--- a/lexilla/lexers/LexErrorList.cxx
+++ b/lexilla/lexers/LexErrorList.cxx
@@ -5,20 +5,21 @@
 // Copyright 1998-2001 by Neil Hodgson <neilh@scintilla.org>
 // The License.txt file describes the conditions under which this software may be distributed.
 
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-#include <stdarg.h>
-#include <assert.h>
-#include <ctype.h>
+#include <cstdlib>
+#include <cassert>
+#include <cstring>
+#include <cstdio>
+#include <cstdarg>
 
 #include <string>
 #include <string_view>
+#include <initializer_list>
 
 #include "ILexer.h"
 #include "Scintilla.h"
 #include "SciLexer.h"
 
+#include "InList.h"
 #include "WordList.h"
 #include "LexAccessor.h"
 #include "Accessor.h"
@@ -42,11 +43,7 @@ constexpr bool Is1To9(char ch) noexcept {
 	return (ch >= '1') && (ch <= '9');
 }
 
-bool IsAlphabetic(int ch) {
-	return IsASCII(ch) && isalpha(ch);
-}
-
-inline bool AtEOL(Accessor &styler, Sci_PositionU i) {
+bool AtEOL(Accessor &styler, Sci_Position i) {
 	return (styler[i] == '\n') ||
 	       ((styler[i] == '\r') && (styler.SafeGetCharAt(i + 1) != '\n'));
 }
@@ -255,18 +252,16 @@ int RecogniseErrorListLine(const char *lineBuffer, Sci_PositionU lengthLine, Sci
 				} else if ((ch == ':' && chNext == ' ') || (ch == ' ')) {
 					// Possibly Delphi.. don't test against chNext as it's one of the strings below.
 					char word[512];
-					unsigned numstep;
+					unsigned numstep = 0;
 					if (ch == ' ')
 						numstep = 1; // ch was ' ', handle as if it's a delphi errorline, only add 1 to i.
 					else
 						numstep = 2; // otherwise add 2.
 					Sci_PositionU chPos = 0;
-					for (Sci_PositionU j = i + numstep; j < lengthLine && IsAlphabetic(lineBuffer[j]) && chPos < sizeof(word) - 1; j++)
+					for (Sci_PositionU j = i + numstep; j < lengthLine && IsUpperOrLowerCase(lineBuffer[j]) && chPos < sizeof(word) - 1; j++)
 						word[chPos++] = lineBuffer[j];
 					word[chPos] = 0;
-					if (!CompareCaseInsensitive(word, "error") || !CompareCaseInsensitive(word, "warning") ||
-						!CompareCaseInsensitive(word, "fatal") || !CompareCaseInsensitive(word, "catastrophic") ||
-						!CompareCaseInsensitive(word, "note") || !CompareCaseInsensitive(word, "remark")) {
+					if (InListCaseInsensitive(word, {"error", "warning", "fatal", "catastrophic", "note", "remark"})) {
 						state = stMsVc;
 					} else {
 						state = stUnrecognized;
@@ -363,12 +358,12 @@ void ColouriseErrorListLine(
 		int portionStyle = style;
 		while (const char *startSeq = strstr(linePortion, CSI)) {
 			if (startSeq > linePortion) {
-				styler.ColourTo(startPortion + static_cast<int>(startSeq - linePortion), portionStyle);
+				styler.ColourTo(startPortion + (startSeq - linePortion), portionStyle);
 			}
 			const char *endSeq = startSeq + 2;
 			while (!SequenceEnd(*endSeq))
 				endSeq++;
-			const Sci_Position endSeqPosition = startPortion + static_cast<Sci_Position>(endSeq - linePortion) + 1;
+			const Sci_Position endSeqPosition = startPortion + (endSeq - linePortion) + 1;
 			switch (*endSeq) {
 			case 0:
 				styler.ColourTo(endPos, SCE_ERR_ESCSEQ_UNKNOWN);
@@ -433,4 +428,4 @@ const char *const emptyWordListDesc[] = {
 
 }
 
-LexerModule lmErrorList(SCLEX_ERRORLIST, ColouriseErrorListDoc, "errorlist", 0, emptyWordListDesc);
+LexerModule lmErrorList(SCLEX_ERRORLIST, ColouriseErrorListDoc, "errorlist", nullptr, emptyWordListDesc);
diff --git a/lexilla/lexers/LexLua.cxx b/lexilla/lexers/LexLua.cxx
index e16ac3a3d..3f0ae3362 100644
--- a/lexilla/lexers/LexLua.cxx
+++ b/lexilla/lexers/LexLua.cxx
@@ -19,7 +19,6 @@
 #include "Scintilla.h"
 #include "SciLexer.h"
 
-#include "StringCopy.h"
 #include "WordList.h"
 #include "LexAccessor.h"
 #include "Accessor.h"
@@ -109,7 +108,7 @@ class LexerLua : public DefaultLexer {
 	OptionSetLua osLua;
 public:
 	explicit LexerLua() :
-		DefaultLexer("lua", SCLEX_LUA, lexicalClasses, ELEMENTS(lexicalClasses)) {
+		DefaultLexer("lua", SCLEX_LUA, lexicalClasses, std::size(lexicalClasses)) {
 	}
 	~LexerLua() override = default;
 	void SCI_METHOD Release() noexcept override {
@@ -324,7 +323,7 @@ void LexerLua::Lex(Sci_PositionU startPos, Sci_Position length, int initStyle, I
 					sc.SetState(SCE_LUA_DEFAULT);
 			}
 		} else if (sc.state == SCE_LUA_IDENTIFIER) {
-			idenPos--;			// commit already-scanned identitier/word parts
+			idenPos--;			// commit already-scanned identifier/word parts
 			if (idenWordPos > 0) {
 				idenWordPos--;
 				sc.ChangeState(idenStyle);
@@ -405,7 +404,7 @@ void LexerLua::Lex(Sci_PositionU startPos, Sci_Position length, int initStyle, I
 		if (sc.state == SCE_LUA_DEFAULT) {
 			if (IsADigit(sc.ch) || (sc.ch == '.' && IsADigit(sc.chNext))) {
 				sc.SetState(SCE_LUA_NUMBER);
-				if (sc.ch == '0' && toupper(sc.chNext) == 'X') {
+				if (sc.ch == '0' && AnyOf(sc.chNext, 'x', 'X')) {
 					sc.Forward();
 				}
 			} else if (setWordStart.Contains(sc.ch)) {
diff --git a/lexilla/lexers/LexPython.cxx b/lexilla/lexers/LexPython.cxx
index 6f29a39f3..212262f4d 100644
--- a/lexilla/lexers/LexPython.cxx
+++ b/lexilla/lexers/LexPython.cxx
@@ -20,7 +20,6 @@
 #include "Scintilla.h"
 #include "SciLexer.h"
 
-#include "StringCopy.h"
 #include "WordList.h"
 #include "LexAccessor.h"
 #include "Accessor.h"
@@ -87,6 +86,9 @@ constexpr bool IsRawPrefix(int ch) {
 }
 
 bool IsPyStringStart(int ch, int chNext, int chNext2, literalsAllowed allowed) noexcept {
+	// To cover both python2 and python3 lex character prefixes as --
+	// ur'' is a string, but ru'' is not
+	// fr'', rf'', br'', rb'' are all strings
 	if (IsQuote(ch))
 		return true;
 	if (IsPyStringTypeChar(ch, allowed)) {
@@ -95,40 +97,39 @@ bool IsPyStringStart(int ch, int chNext, int chNext2, literalsAllowed allowed) n
 		if (IsRawPrefix(chNext) && IsQuote(chNext2))
 			return true;
 	}
-	if (IsRawPrefix(ch) && IsQuote(chNext))
-		return true;
+	if (IsRawPrefix(ch)) {
+		if (IsQuote(chNext))
+			return true;
+		if (IsPyStringTypeChar(chNext, allowed) && !AnyOf(chNext, 'u', 'U') && IsQuote(chNext2))
+			return true;
+	}
 
 	return false;
 }
 
 constexpr bool IsPyFStringState(int st) noexcept {
-	return ((st == SCE_P_FCHARACTER) || (st == SCE_P_FSTRING) ||
-		(st == SCE_P_FTRIPLE) || (st == SCE_P_FTRIPLEDOUBLE));
+	return AnyOf(st, SCE_P_FCHARACTER, SCE_P_FSTRING, SCE_P_FTRIPLE, SCE_P_FTRIPLEDOUBLE);
 }
 
 constexpr bool IsPySingleQuoteStringState(int st) noexcept {
-	return ((st == SCE_P_CHARACTER) || (st == SCE_P_STRING) ||
-		(st == SCE_P_FCHARACTER) || (st == SCE_P_FSTRING));
+	return AnyOf(st, SCE_P_CHARACTER, SCE_P_STRING, SCE_P_FCHARACTER, SCE_P_FSTRING);
 }
 
 constexpr bool IsPyTripleQuoteStringState(int st) noexcept {
-	return ((st == SCE_P_TRIPLE) || (st == SCE_P_TRIPLEDOUBLE) ||
-		(st == SCE_P_FTRIPLE) || (st == SCE_P_FTRIPLEDOUBLE));
+	return AnyOf(st, SCE_P_TRIPLE, SCE_P_TRIPLEDOUBLE, SCE_P_FTRIPLE, SCE_P_FTRIPLEDOUBLE);
 }
 
 char GetPyStringQuoteChar(int st) noexcept {
-	if ((st == SCE_P_CHARACTER) || (st == SCE_P_FCHARACTER) ||
-			(st == SCE_P_TRIPLE) || (st == SCE_P_FTRIPLE))
+	if (AnyOf(st, SCE_P_CHARACTER, SCE_P_FCHARACTER, SCE_P_TRIPLE, SCE_P_FTRIPLE))
 		return '\'';
-	if ((st == SCE_P_STRING) || (st == SCE_P_FSTRING) ||
-			(st == SCE_P_TRIPLEDOUBLE) || (st == SCE_P_FTRIPLEDOUBLE))
+	if (AnyOf(st, SCE_P_STRING, SCE_P_FSTRING, SCE_P_TRIPLEDOUBLE, SCE_P_FTRIPLEDOUBLE))
 		return '"';
 
 	return '\0';
 }
 
 void PushStateToStack(int state, std::vector<SingleFStringExpState> &stack, SingleFStringExpState *&currentFStringExp) {
-	SingleFStringExpState single = {state, 0};
+	const SingleFStringExpState single = {state, 0};
 	stack.push_back(single);
 
 	currentFStringExp = &stack.back();
@@ -155,14 +156,22 @@ int PopFromStateStack(std::vector<SingleFStringExpState> &stack, SingleFStringEx
 int GetPyStringState(Accessor &styler, Sci_Position i, Sci_PositionU *nextIndex, literalsAllowed allowed) {
 	char ch = styler.SafeGetCharAt(i);
 	char chNext = styler.SafeGetCharAt(i + 1);
-	const int firstIsF = (ch == 'f' || ch == 'F');
+	bool isFString = false;
 
-	// Advance beyond r, u, or ur prefix (or r, b, or br in Python 2.7+ and r, f, or fr in Python 3.6+), but bail if there are any unexpected chars
+	// Advance beyond r, a type char, or both (in either order)
+	// Note that this depends on IsPyStringStart to enforce ru'' not being a string
 	if (IsRawPrefix(ch)) {
 		i++;
+		if (IsPyStringTypeChar(chNext, allowed)) {
+			if (AnyOf(chNext, 'f', 'F'))
+				isFString = true;
+			i++;
+		}
 		ch = styler.SafeGetCharAt(i);
 		chNext = styler.SafeGetCharAt(i + 1);
 	} else if (IsPyStringTypeChar(ch, allowed)) {
+		if (AnyOf(ch, 'f', 'F'))
+			isFString = true;
 		if (IsRawPrefix(chNext))
 			i += 2;
 		else
@@ -171,6 +180,7 @@ int GetPyStringState(Accessor &styler, Sci_Position i, Sci_PositionU *nextIndex,
 		chNext = styler.SafeGetCharAt(i + 1);
 	}
 
+	// ch and i will be the first quote
 	if (!IsQuote(ch)) {
 		*nextIndex = i + 1;
 		return SCE_P_DEFAULT;
@@ -180,16 +190,16 @@ int GetPyStringState(Accessor &styler, Sci_Position i, Sci_PositionU *nextIndex,
 		*nextIndex = i + 3;
 
 		if (ch == '"')
-			return (firstIsF ? SCE_P_FTRIPLEDOUBLE : SCE_P_TRIPLEDOUBLE);
+			return (isFString ? SCE_P_FTRIPLEDOUBLE : SCE_P_TRIPLEDOUBLE);
 		else
-			return (firstIsF ? SCE_P_FTRIPLE : SCE_P_TRIPLE);
+			return (isFString ? SCE_P_FTRIPLE : SCE_P_TRIPLE);
 	} else {
 		*nextIndex = i + 1;
 
 		if (ch == '"')
-			return (firstIsF ? SCE_P_FSTRING : SCE_P_STRING);
+			return (isFString ? SCE_P_FSTRING : SCE_P_STRING);
 		else
-			return (firstIsF ? SCE_P_FCHARACTER : SCE_P_CHARACTER);
+			return (isFString ? SCE_P_FCHARACTER : SCE_P_CHARACTER);
 	}
 }
 
@@ -362,7 +372,7 @@ struct OptionSetPython : public OptionSet<OptionsPython> {
 
 const char styleSubable[] = { SCE_P_IDENTIFIER, 0 };
 
-LexicalClass lexicalClasses[] = {
+const LexicalClass lexicalClasses[] = {
 	// Lexer Python SCLEX_PYTHON SCE_P_:
 	0, "SCE_P_DEFAULT", "default", "White space",
 	1, "SCE_P_COMMENTLINE", "comment line", "Comment",
@@ -387,8 +397,6 @@ LexicalClass lexicalClasses[] = {
 	20, "SCE_P_ATTRIBUTE", "identifier", "Attribute of identifier",
 };
 
-}
-
 class LexerPython : public DefaultLexer {
 	WordList keywords;
 	WordList keywords2;
@@ -399,7 +407,7 @@ class LexerPython : public DefaultLexer {
 	std::map<Sci_Position, std::vector<SingleFStringExpState> > ftripleStateAtEol;
 public:
 	explicit LexerPython() :
-		DefaultLexer("python", SCLEX_PYTHON, lexicalClasses, ELEMENTS(lexicalClasses)),
+		DefaultLexer("python", SCLEX_PYTHON, lexicalClasses, std::size(lexicalClasses)),
 		subStyles(styleSubable, 0x80, 0x40, 0) {
 	}
 	~LexerPython() override = default;
@@ -568,10 +576,8 @@ void SCI_METHOD LexerPython::Lex(Sci_PositionU startPos, Sci_Position length, in
 			// Look for backslash-continued lines
 			while (lineCurrent > 0) {
 				const Sci_Position eolPos = styler.LineStart(lineCurrent) - 1;
-				const int eolStyle = styler.StyleAt(eolPos);
-				if (eolStyle == SCE_P_STRING
-						|| eolStyle == SCE_P_CHARACTER
-						|| eolStyle == SCE_P_STRINGEOL) {
+				const int eolStyle = styler.StyleIndexAt(eolPos);
+				if (AnyOf(eolStyle, SCE_P_STRING, SCE_P_CHARACTER, SCE_P_STRINGEOL)) {
 					lineCurrent -= 1;
 				} else {
 					break;
@@ -579,7 +585,7 @@ void SCI_METHOD LexerPython::Lex(Sci_PositionU startPos, Sci_Position length, in
 			}
 			startPos = styler.LineStart(lineCurrent);
 		}
-		initStyle = startPos == 0 ? SCE_P_DEFAULT : styler.StyleAt(startPos - 1);
+		initStyle = startPos == 0 ? SCE_P_DEFAULT : styler.StyleIndexAt(startPos - 1);
 	}
 
 	const literalsAllowed allowedLiterals = options.AllowedLiterals();
@@ -653,12 +659,12 @@ void SCI_METHOD LexerPython::Lex(Sci_PositionU startPos, Sci_Position length, in
 			}
 		} else if (sc.state == SCE_P_IDENTIFIER) {
 			if ((sc.ch == '.') || (!IsAWordChar(sc.ch, options.unicodeIdentifiers))) {
-				char s[100];
-				sc.GetCurrent(s, sizeof(s));
+				char identifier[100];
+				sc.GetCurrent(identifier, sizeof(identifier));
 				int style = SCE_P_IDENTIFIER;
-				if ((kwLast == kwImport) && (strcmp(s, "as") == 0)) {
+				if ((kwLast == kwImport) && (strcmp(identifier, "as") == 0)) {
 					style = SCE_P_WORD;
-				} else if (keywords.InList(s) && !IsMatchOrCaseIdentifier(sc, styler, s)) {
+				} else if (keywords.InList(identifier) && !IsMatchOrCaseIdentifier(sc, styler, identifier)) {
 					style = SCE_P_WORD;
 				} else if (kwLast == kwClass) {
 					style = SCE_P_CLASSNAME;
@@ -681,7 +687,7 @@ void SCI_METHOD LexerPython::Lex(Sci_PositionU startPos, Sci_Position length, in
 							break;
 						}
 					}
-				} else if (keywords2.InList(s)) {
+				} else if (keywords2.InList(identifier)) {
 					if (options.keywords2NoSubIdentifiers) {
 						// We don't want to highlight keywords2
 						// that are used as a sub-identifier,
@@ -693,7 +699,7 @@ void SCI_METHOD LexerPython::Lex(Sci_PositionU startPos, Sci_Position length, in
 						style = SCE_P_WORD2;
 					}
 				} else {
-					const int subStyle = classifierIdentifiers.ValueFor(s);
+					const int subStyle = classifierIdentifiers.ValueFor(identifier);
 					if (subStyle >= 0) {
 						style = subStyle;
 					}
@@ -738,17 +744,17 @@ void SCI_METHOD LexerPython::Lex(Sci_PositionU startPos, Sci_Position length, in
 				sc.ChangeState(style);
 				sc.SetState(SCE_P_DEFAULT);
 				if (style == SCE_P_WORD) {
-					if (0 == strcmp(s, "class"))
+					if (0 == strcmp(identifier, "class"))
 						kwLast = kwClass;
-					else if (0 == strcmp(s, "def"))
+					else if (0 == strcmp(identifier, "def"))
 						kwLast = kwDef;
-					else if (0 == strcmp(s, "import"))
+					else if (0 == strcmp(identifier, "import"))
 						kwLast = kwImport;
-					else if (0 == strcmp(s, "cdef"))
+					else if (0 == strcmp(identifier, "cdef"))
 						kwLast = kwCDef;
-					else if (0 == strcmp(s, "cpdef"))
+					else if (0 == strcmp(identifier, "cpdef"))
 						kwLast = kwCPDef;
-					else if (0 == strcmp(s, "cimport"))
+					else if (0 == strcmp(identifier, "cimport"))
 						kwLast = kwImport;
 					else if (kwLast != kwCDef && kwLast != kwCPDef)
 						kwLast = kwOther;
@@ -922,21 +928,21 @@ void SCI_METHOD LexerPython::Lex(Sci_PositionU startPos, Sci_Position length, in
 	sc.Complete();
 }
 
-static bool IsCommentLine(Sci_Position line, Accessor &styler) {
+bool IsCommentLine(Sci_Position line, Accessor &styler) {
 	const Sci_Position pos = styler.LineStart(line);
 	const Sci_Position eol_pos = styler.LineStart(line + 1) - 1;
 	for (Sci_Position i = pos; i < eol_pos; i++) {
 		const char ch = styler[i];
 		if (ch == '#')
 			return true;
-		else if (ch != ' ' && ch != '\t')
+		if (!IsASpaceOrTab(ch))
 			return false;
 	}
 	return false;
 }
 
-static bool IsQuoteLine(Sci_Position line, const Accessor &styler) {
-	const int style = styler.StyleAt(styler.LineStart(line));
+bool IsQuoteLine(Sci_Position line, const Accessor &styler) {
+	const int style = styler.StyleIndexAt(styler.LineStart(line));
 	return IsPyTripleQuoteStringState(style);
 }
 
@@ -972,7 +978,7 @@ void SCI_METHOD LexerPython::Fold(Sci_PositionU startPos, Sci_Position length, i
 	startPos = styler.LineStart(lineCurrent);
 	int prev_state = SCE_P_DEFAULT;
 	if (lineCurrent >= 1)
-		prev_state = styler.StyleAt(startPos - 1);
+		prev_state = styler.StyleIndexAt(startPos - 1);
 	int prevQuote = options.foldQuotes && IsPyTripleQuoteStringState(prev_state);
 
 	// Process all characters to end of requested range or end of any triple quote
@@ -989,7 +995,7 @@ void SCI_METHOD LexerPython::Fold(Sci_PositionU startPos, Sci_Position length, i
 			// Information about next line is only available if not at end of document
 			indentNext = styler.IndentAmount(lineNext, &spaceFlags, nullptr);
 			const Sci_Position lookAtPos = (styler.LineStart(lineNext) == styler.Length()) ? styler.Length() - 1 : styler.LineStart(lineNext);
-			const int style = styler.StyleAt(lookAtPos);
+			const int style = styler.StyleIndexAt(lookAtPos);
 			quote = options.foldQuotes && IsPyTripleQuoteStringState(style);
 		}
 		const bool quote_start = (quote && !prevQuote);
@@ -1079,5 +1085,7 @@ void SCI_METHOD LexerPython::Fold(Sci_PositionU startPos, Sci_Position length, i
 	//styler.SetLevel(lineCurrent, indentCurrent);
 }
 
+}
+
 LexerModule lmPython(SCLEX_PYTHON, LexerPython::LexerFactoryPython, "python",
 		     pythonWordListDesc);
diff --git a/lexilla/lexers/LexRuby.cxx b/lexilla/lexers/LexRuby.cxx
index 77c97f80e..8ac792d1d 100644
--- a/lexilla/lexers/LexRuby.cxx
+++ b/lexilla/lexers/LexRuby.cxx
@@ -747,9 +747,6 @@ void ColouriseRbDoc(Sci_PositionU startPos, Sci_Position length, int initStyle,
 
     QuoteCls Quote;
 
-    int numDots = 0;  // For numbers --
-    // Don't start lexing in the middle of a num
-
     synchronizeDocStart(startPos, length, initStyle, styler, false);
 
     bool preferRE = true;
@@ -880,7 +877,6 @@ void ColouriseRbDoc(Sci_PositionU startPos, Sci_Position length, int initStyle,
                 styler.ColourTo(i - 1, state);
                 state = SCE_RB_NUMBER;
                 is_real_number = true;
-                numDots = 0;
             } else if (isHighBitChar(ch) || iswordstart(ch)) {
                 styler.ColourTo(i - 1, state);
                 state = SCE_RB_WORD;
@@ -1285,14 +1281,11 @@ void ColouriseRbDoc(Sci_PositionU startPos, Sci_Position length, int initStyle,
                     preferRE = false;
                     advance_char(i, ch, chNext, chNext2);
                 }
-            } else if (isSafeAlnumOrHigh(ch) || ch == '_') {
+            } else if (isSafeAlnumOrHigh(ch) || ch == '_' || (ch == '.' && isSafeDigit(chNext))) {
                 // Keep going
             } else if (ch == '.' && chNext == '.') {
-                ++numDots;
                 styler.ColourTo(i - 1, state);
                 redo_char(i, ch, chNext, chNext2, state); // pass by ref
-            } else if (ch == '.' && ++numDots == 1) {
-                // Keep going
             } else {
                 styler.ColourTo(i - 1, state);
                 redo_char(i, ch, chNext, chNext2, state); // pass by ref
diff --git a/lexilla/lexlib/CharacterSet.cxx b/lexilla/lexlib/CharacterSet.cxx
index 1b6770052..619776db2 100644
--- a/lexilla/lexlib/CharacterSet.cxx
+++ b/lexilla/lexlib/CharacterSet.cxx
@@ -9,6 +9,8 @@
 #include <cstdlib>
 #include <cassert>
 
+#include <string_view>
+
 #include "CharacterSet.h"
 
 using namespace Lexilla;
@@ -30,6 +32,18 @@ int CompareCaseInsensitive(const char *a, const char *b) noexcept {
 	return *a - *b;
 }
 
+bool EqualCaseInsensitive(std::string_view a, std::string_view b) noexcept {
+	if (a.length() != b.length()) {
+		return false;
+	}
+	for (size_t i = 0; i < a.length(); i++) {
+		if (MakeUpperCase(a[i]) != MakeUpperCase(b[i])) {
+			return false;
+		}
+	}
+	return true;
+}
+
 int CompareNCaseInsensitive(const char *a, const char *b, size_t len) noexcept {
 	while (*a && *b && len) {
 		if (*a != *b) {
diff --git a/lexilla/lexlib/CharacterSet.h b/lexilla/lexlib/CharacterSet.h
index 5b0486e42..3b1f4890e 100644
--- a/lexilla/lexlib/CharacterSet.h
+++ b/lexilla/lexlib/CharacterSet.h
@@ -187,6 +187,7 @@ constexpr T MakeLowerCase(T ch) noexcept {
 }
 
 int CompareCaseInsensitive(const char *a, const char *b) noexcept;
+bool EqualCaseInsensitive(std::string_view a, std::string_view b) noexcept;
 int CompareNCaseInsensitive(const char *a, const char *b, size_t len) noexcept;
 
 }
diff --git a/lexilla/lexlib/InList.cxx b/lexilla/lexlib/InList.cxx
new file mode 100644
index 000000000..4d7b75174
--- /dev/null
+++ b/lexilla/lexlib/InList.cxx
@@ -0,0 +1,37 @@
+// Scintilla source code edit control
+/** @file InList.cxx
+ ** Check if a string is in a list.
+ **/
+// Copyright 2024 by Neil Hodgson <neilh@scintilla.org>
+// The License.txt file describes the conditions under which this software may be distributed.
+
+#include <cassert>
+
+#include <string>
+#include <string_view>
+#include <initializer_list>
+
+#include "InList.h"
+#include "CharacterSet.h"
+
+namespace Lexilla {
+
+bool InList(std::string_view value, std::initializer_list<std::string_view> list) noexcept {
+	for (const std::string_view element : list) {
+		if (value == element) {
+			return true;
+		}
+	}
+	return false;
+}
+
+bool InListCaseInsensitive(std::string_view value, std::initializer_list<std::string_view> list) noexcept {
+	for (const std::string_view element : list) {
+		if (EqualCaseInsensitive(value, element)) {
+			return true;
+		}
+	}
+	return false;
+}
+
+}
diff --git a/lexilla/lexlib/InList.h b/lexilla/lexlib/InList.h
new file mode 100644
index 000000000..9e52ff6f0
--- /dev/null
+++ b/lexilla/lexlib/InList.h
@@ -0,0 +1,18 @@
+// Scintilla source code edit control
+/** @file InList.h
+ ** Check if a string is in a list.
+ **/
+// Copyright 2024 by Neil Hodgson <neilh@scintilla.org>
+// The License.txt file describes the conditions under which this software may be distributed.
+
+#ifndef INLIST_H
+#define INLIST_H
+
+namespace Lexilla {
+
+bool InList(std::string_view value, std::initializer_list<std::string_view> list) noexcept;
+bool InListCaseInsensitive(std::string_view value, std::initializer_list<std::string_view> list) noexcept;
+
+}
+
+#endif
diff --git a/lexilla/lexlib/OptionSet.h b/lexilla/lexlib/OptionSet.h
index 09f6058ba..6abedc00d 100644
--- a/lexilla/lexlib/OptionSet.h
+++ b/lexilla/lexlib/OptionSet.h
@@ -97,6 +97,15 @@ public:
 		nameToDef[name] = Option(ps, description);
 		AppendName(name);
 	}
+	template <typename E>
+	void DefineProperty(const char *name, E T::*pe, std::string_view description="") {
+		static_assert(std::is_enum<E>::value);
+		plcoi pi {};
+		static_assert(sizeof(pe) == sizeof(pi));
+		memcpy(&pi, &pe, sizeof(pe));
+		nameToDef[name] = Option(pi, description);
+		AppendName(name);
+	}
 	const char *PropertyNames() const noexcept {
 		return names.c_str();
 	}
diff --git a/lexilla/lexlib/WordList.cxx b/lexilla/lexlib/WordList.cxx
index 5cab08142..b2ce00f07 100644
--- a/lexilla/lexlib/WordList.cxx
+++ b/lexilla/lexlib/WordList.cxx
@@ -242,7 +242,7 @@ bool WordList::InListAbbreviated(const char *s, const char marker) const noexcep
 	return false;
 }
 
-/** similar to InListAbbreviated, but word s can be a abridged version of a keyword.
+/** similar to InListAbbreviated, but word s can be an abridged version of a keyword.
 * eg. the keyword is defined as "after.~:". This means the word must have a prefix (begins with) of
 * "after." and suffix (ends with) of ":" to be a keyword, Hence "after.field:" , "after.form.item:" are valid.
 * Similarly "~.is.valid" keyword is suffix only... hence "field.is.valid" , "form.is.valid" are valid.
diff --git a/lexilla/lexlib/WordList.h b/lexilla/lexlib/WordList.h
index 71d5bea02..6d73ca86a 100644
--- a/lexilla/lexlib/WordList.h
+++ b/lexilla/lexlib/WordList.h
@@ -13,7 +13,7 @@ namespace Lexilla {
 /**
  */
 class WordList {
-	// Each word contains at least one character - a empty word acts as sentinel at the end.
+	// Each word contains at least one character - an empty word acts as sentinel at the end.
 	char **words;
 	char *list;
 	size_t len;
diff --git a/lexilla/scripts/HeaderOrder.txt b/lexilla/scripts/HeaderOrder.txt
index a4b3046e5..71f5807f9 100644
--- a/lexilla/scripts/HeaderOrder.txt
+++ b/lexilla/scripts/HeaderOrder.txt
@@ -81,6 +81,7 @@
 // lexlib
 #include "StringCopy.h"
 #include "PropSetSimple.h"
+#include "InList.h"
 #include "WordList.h"
 #include "LexAccessor.h"
 #include "Accessor.h"
diff --git a/lexilla/src/Lexilla/Info.plist b/lexilla/src/Lexilla/Info.plist
index e4bc4369b..0bfba2a42 100644
--- a/lexilla/src/Lexilla/Info.plist
+++ b/lexilla/src/Lexilla/Info.plist
@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>$(PRODUCT_BUNDLE_PACKAGE_TYPE)</string>
 	<key>CFBundleShortVersionString</key>
-	<string>5.3.0</string>
+	<string>5.3.1</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 	<key>NSHumanReadableCopyright</key>
diff --git a/lexilla/src/Lexilla/Lexilla.xcodeproj/project.pbxproj b/lexilla/src/Lexilla/Lexilla.xcodeproj/project.pbxproj
index 4cdc8d28c..dc70bebf4 100644
--- a/lexilla/src/Lexilla/Lexilla.xcodeproj/project.pbxproj
+++ b/lexilla/src/Lexilla/Lexilla.xcodeproj/project.pbxproj
@@ -9,6 +9,8 @@
 /* Begin PBXBuildFile section */
 		00D544CC992062D2E3CD4BF6 /* LexGDScript.cxx in Sources */ = {isa = PBXBuildFile; fileRef = A383409E9A994F461550FEC1 /* LexGDScript.cxx */; };
 		283639BC268FD4EA009D58A1 /* LexAccessor.cxx in Sources */ = {isa = PBXBuildFile; fileRef = 283639BB268FD4EA009D58A1 /* LexAccessor.cxx */; };
+		283A17AE2B47E61100DF5C82 /* InList.cxx in Sources */ = {isa = PBXBuildFile; fileRef = 283A17AC2B47E61100DF5C82 /* InList.cxx */; };
+		283A17AF2B47E61100DF5C82 /* InList.h in Headers */ = {isa = PBXBuildFile; fileRef = 283A17AD2B47E61100DF5C82 /* InList.h */; };
 		28BA72AB24E34D5B00272C2D /* LexerBase.cxx in Sources */ = {isa = PBXBuildFile; fileRef = 28BA728F24E34D5A00272C2D /* LexerBase.cxx */; };
 		28BA72AC24E34D5B00272C2D /* LexAccessor.h in Headers */ = {isa = PBXBuildFile; fileRef = 28BA729024E34D5A00272C2D /* LexAccessor.h */; };
 		28BA72AD24E34D5B00272C2D /* DefaultLexer.h in Headers */ = {isa = PBXBuildFile; fileRef = 28BA729124E34D5A00272C2D /* DefaultLexer.h */; };
@@ -161,6 +163,8 @@
 /* Begin PBXFileReference section */
 		280262A5246DF655000DF3B8 /* liblexilla.dylib */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.dylib"; includeInIndex = 0; path = liblexilla.dylib; sourceTree = BUILT_PRODUCTS_DIR; };
 		283639BB268FD4EA009D58A1 /* LexAccessor.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = LexAccessor.cxx; path = ../../lexlib/LexAccessor.cxx; sourceTree = "<group>"; };
+		283A17AC2B47E61100DF5C82 /* InList.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = InList.cxx; path = ../../lexlib/InList.cxx; sourceTree = "<group>"; };
+		283A17AD2B47E61100DF5C82 /* InList.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = InList.h; path = ../../lexlib/InList.h; sourceTree = "<group>"; };
 		28BA728F24E34D5A00272C2D /* LexerBase.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = LexerBase.cxx; path = ../../lexlib/LexerBase.cxx; sourceTree = "<group>"; };
 		28BA729024E34D5A00272C2D /* LexAccessor.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = LexAccessor.h; path = ../../lexlib/LexAccessor.h; sourceTree = "<group>"; };
 		28BA729124E34D5A00272C2D /* DefaultLexer.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = DefaultLexer.h; path = ../../lexlib/DefaultLexer.h; sourceTree = "<group>"; };
@@ -488,6 +492,8 @@
 				28BA72A124E34D5B00272C2D /* CharacterSet.h */,
 				28BA729C24E34D5A00272C2D /* DefaultLexer.cxx */,
 				28BA729124E34D5A00272C2D /* DefaultLexer.h */,
+				283A17AC2B47E61100DF5C82 /* InList.cxx */,
+				283A17AD2B47E61100DF5C82 /* InList.h */,
 				283639BB268FD4EA009D58A1 /* LexAccessor.cxx */,
 				28BA729024E34D5A00272C2D /* LexAccessor.h */,
 				28BA728F24E34D5A00272C2D /* LexerBase.cxx */,
@@ -529,6 +535,7 @@
 				28BA72B324E34D5B00272C2D /* Accessor.h in Headers */,
 				28BA72BE24E34D5B00272C2D /* StyleContext.h in Headers */,
 				28BA72BB24E34D5B00272C2D /* OptionSet.h in Headers */,
+				283A17AF2B47E61100DF5C82 /* InList.h in Headers */,
 				28BA72B024E34D5B00272C2D /* LexerModule.h in Headers */,
 				28BA72AC24E34D5B00272C2D /* LexAccessor.h in Headers */,
 				28BA72C524E34D5B00272C2D /* CharacterCategory.h in Headers */,
@@ -684,6 +691,7 @@
 				28BA73A624E34D9700272C2D /* LexMatlab.cxx in Sources */,
 				28BA736324E34D9700272C2D /* LexRaku.cxx in Sources */,
 				28BA736224E34D9700272C2D /* LexCPP.cxx in Sources */,
+				283A17AE2B47E61100DF5C82 /* InList.cxx in Sources */,
 				28BA738A24E34D9700272C2D /* LexOpal.cxx in Sources */,
 				28BA736E24E34D9700272C2D /* LexRegistry.cxx in Sources */,
 				28BA738224E34D9700272C2D /* LexMMIXAL.cxx in Sources */,
@@ -858,7 +866,7 @@
 			buildSettings = {
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++17";
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 5.3.0;
+				CURRENT_PROJECT_VERSION = 5.3.1;
 				DEAD_CODE_STRIPPING = YES;
 				DEVELOPMENT_TEAM = 4F446KW87E;
 				DYLIB_COMPATIBILITY_VERSION = 1;
@@ -886,7 +894,7 @@
 			buildSettings = {
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++17";
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 5.3.0;
+				CURRENT_PROJECT_VERSION = 5.3.1;
 				DEAD_CODE_STRIPPING = YES;
 				DEVELOPMENT_TEAM = 4F446KW87E;
 				DYLIB_COMPATIBILITY_VERSION = 1;
diff --git a/lexilla/src/LexillaVersion.rc b/lexilla/src/LexillaVersion.rc
index 2857dd455..d8adacea6 100644
--- a/lexilla/src/LexillaVersion.rc
+++ b/lexilla/src/LexillaVersion.rc
@@ -4,8 +4,8 @@
 
 #include <windows.h>
 
-#define VERSION_LEXILLA "5.3.0"
-#define VERSION_WORDS 5, 3, 0, 0
+#define VERSION_LEXILLA "5.3.1"
+#define VERSION_WORDS 5, 3, 1, 0
 
 VS_VERSION_INFO VERSIONINFO
 FILEVERSION	VERSION_WORDS
diff --git a/lexilla/src/deps.mak b/lexilla/src/deps.mak
index 34120eaed..099254404 100644
--- a/lexilla/src/deps.mak
+++ b/lexilla/src/deps.mak
@@ -33,6 +33,10 @@ $(DIR_O)/DefaultLexer.o: \
 	../lexlib/Accessor.h \
 	../lexlib/LexerModule.h \
 	../lexlib/DefaultLexer.h
+$(DIR_O)/InList.o: \
+	../lexlib/InList.cxx \
+	../lexlib/InList.h \
+	../lexlib/CharacterSet.h
 $(DIR_O)/LexAccessor.o: \
 	../lexlib/LexAccessor.cxx \
 	../../scintilla/include/ILexer.h \
@@ -257,6 +261,7 @@ $(DIR_O)/LexBash.o: \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
 	../lexlib/StringCopy.h \
+	../lexlib/InList.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/StyleContext.h \
@@ -284,6 +289,7 @@ $(DIR_O)/LexBatch.o: \
 	../../scintilla/include/Sci_Position.h \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
+	../lexlib/InList.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/Accessor.h \
@@ -568,6 +574,7 @@ $(DIR_O)/LexErrorList.o: \
 	../../scintilla/include/Sci_Position.h \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
+	../lexlib/InList.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/Accessor.h \
@@ -854,7 +861,6 @@ $(DIR_O)/LexLua.o: \
 	../../scintilla/include/Sci_Position.h \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
-	../lexlib/StringCopy.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/Accessor.h \
@@ -1212,7 +1218,6 @@ $(DIR_O)/LexPython.o: \
 	../../scintilla/include/Sci_Position.h \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
-	../lexlib/StringCopy.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/Accessor.h \
diff --git a/lexilla/src/lexilla.mak b/lexilla/src/lexilla.mak
index e02af7236..197c96e30 100644
--- a/lexilla/src/lexilla.mak
+++ b/lexilla/src/lexilla.mak
@@ -209,6 +209,7 @@ LEXLIB_OBJS=\
 	$(DIR_O)\CharacterCategory.obj \
 	$(DIR_O)\CharacterSet.obj \
 	$(DIR_O)\DefaultLexer.obj \
+	$(DIR_O)\InList.obj \
 	$(DIR_O)\LexAccessor.obj \
 	$(DIR_O)\LexerBase.obj \
 	$(DIR_O)\LexerModule.obj \
diff --git a/lexilla/src/makefile b/lexilla/src/makefile
index c16e6784b..48da3886f 100644
--- a/lexilla/src/makefile
+++ b/lexilla/src/makefile
@@ -116,6 +116,7 @@ LEXLIB_OBJS=\
 	CharacterCategory.o \
 	CharacterSet.o \
 	DefaultLexer.o \
+	InList.o \
 	LexAccessor.o \
 	LexerBase.o \
 	LexerModule.o \
diff --git a/lexilla/src/nmdeps.mak b/lexilla/src/nmdeps.mak
index 5f1307f98..ef7d1fef6 100644
--- a/lexilla/src/nmdeps.mak
+++ b/lexilla/src/nmdeps.mak
@@ -33,6 +33,10 @@ $(DIR_O)/DefaultLexer.obj: \
 	../lexlib/Accessor.h \
 	../lexlib/LexerModule.h \
 	../lexlib/DefaultLexer.h
+$(DIR_O)/InList.obj: \
+	../lexlib/InList.cxx \
+	../lexlib/InList.h \
+	../lexlib/CharacterSet.h
 $(DIR_O)/LexAccessor.obj: \
 	../lexlib/LexAccessor.cxx \
 	../../scintilla/include/ILexer.h \
@@ -257,6 +261,7 @@ $(DIR_O)/LexBash.obj: \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
 	../lexlib/StringCopy.h \
+	../lexlib/InList.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/StyleContext.h \
@@ -284,6 +289,7 @@ $(DIR_O)/LexBatch.obj: \
 	../../scintilla/include/Sci_Position.h \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
+	../lexlib/InList.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/Accessor.h \
@@ -568,6 +574,7 @@ $(DIR_O)/LexErrorList.obj: \
 	../../scintilla/include/Sci_Position.h \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
+	../lexlib/InList.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/Accessor.h \
@@ -854,7 +861,6 @@ $(DIR_O)/LexLua.obj: \
 	../../scintilla/include/Sci_Position.h \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
-	../lexlib/StringCopy.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/Accessor.h \
@@ -1212,7 +1218,6 @@ $(DIR_O)/LexPython.obj: \
 	../../scintilla/include/Sci_Position.h \
 	../../scintilla/include/Scintilla.h \
 	../include/SciLexer.h \
-	../lexlib/StringCopy.h \
 	../lexlib/WordList.h \
 	../lexlib/LexAccessor.h \
 	../lexlib/Accessor.h \
diff --git a/lexilla/test/examples/asm/AllStyles.asm b/lexilla/test/examples/asm/AllStyles.asm
new file mode 100644
index 000000000..251666228
--- /dev/null
+++ b/lexilla/test/examples/asm/AllStyles.asm
@@ -0,0 +1,52 @@
+; Enumerate all styles: 0 to 15 except for 11(comment block) which is not yet implemented.
+; This is not a viable source file, it just illustrates the different states in isolation.
+
+; comment=1
+; Comment
+
+; whitespace=0
+	; w
+
+; number=2
+11
+
+; string=3
+"String"
+
+; operator=4
++
+
+; identifier=5
+identifier
+
+; CPU instruction=6
+add
+
+; math Instruction=7
+fadd
+
+; register=8
+ECX
+
+; directive=9
+section
+
+; directive operand=10
+rel
+
+; comment block=11 is for future expansion
+
+; character=12
+'character'
+
+; string EOL=13
+"no line end
+
+; extended instruction=14
+movq
+
+; comment directive=15
+ comment ~ A multiple-line
+ comment directive~
+
+;end
diff --git a/lexilla/test/examples/asm/AllStyles.asm.folded b/lexilla/test/examples/asm/AllStyles.asm.folded
new file mode 100644
index 000000000..6fe027cf8
--- /dev/null
+++ b/lexilla/test/examples/asm/AllStyles.asm.folded
@@ -0,0 +1,53 @@
+ 0 400   0   ; Enumerate all styles: 0 to 15 except for 11(comment block) which is not yet implemented.
+ 0 400   0   ; This is not a viable source file, it just illustrates the different states in isolation.
+ 0 400   0   
+ 0 400   0   ; comment=1
+ 0 400   0   ; Comment
+ 0 400   0   
+ 0 400   0   ; whitespace=0
+ 0 400   0   	; w
+ 0 400   0   
+ 0 400   0   ; number=2
+ 0 400   0   11
+ 0 400   0   
+ 0 400   0   ; string=3
+ 0 400   0   "String"
+ 0 400   0   
+ 0 400   0   ; operator=4
+ 0 400   0   +
+ 0 400   0   
+ 0 400   0   ; identifier=5
+ 0 400   0   identifier
+ 0 400   0   
+ 0 400   0   ; CPU instruction=6
+ 0 400   0   add
+ 0 400   0   
+ 0 400   0   ; math Instruction=7
+ 0 400   0   fadd
+ 0 400   0   
+ 0 400   0   ; register=8
+ 0 400   0   ECX
+ 0 400   0   
+ 0 400   0   ; directive=9
+ 0 400   0   section
+ 0 400   0   
+ 0 400   0   ; directive operand=10
+ 0 400   0   rel
+ 0 400   0   
+ 0 400   0   ; comment block=11 is for future expansion
+ 0 400   0   
+ 0 400   0   ; character=12
+ 0 400   0   'character'
+ 0 400   0   
+ 0 400   0   ; string EOL=13
+ 0 400   0   "no line end
+ 0 400   0   
+ 0 400   0   ; extended instruction=14
+ 0 400   0   movq
+ 0 400   0   
+ 0 400   0   ; comment directive=15
+ 0 400   0    comment ~ A multiple-line
+ 0 400   0    comment directive~
+ 0 400   0   
+ 0 400   0   ;end
+ 0 400   0   
\ No newline at end of file
diff --git a/lexilla/test/examples/asm/AllStyles.asm.styled b/lexilla/test/examples/asm/AllStyles.asm.styled
new file mode 100644
index 000000000..74d82cb5d
--- /dev/null
+++ b/lexilla/test/examples/asm/AllStyles.asm.styled
@@ -0,0 +1,52 @@
+{1}; Enumerate all styles: 0 to 15 except for 11(comment block) which is not yet implemented.
+; This is not a viable source file, it just illustrates the different states in isolation.
+{0}
+{1}; comment=1
+; Comment
+{0}
+{1}; whitespace=0
+{0}	{1}; w
+{0}
+{1}; number=2
+{2}11{0}
+
+{1}; string=3
+{3}"String"{0}
+
+{1}; operator=4
+{4}+{0}
+
+{1}; identifier=5
+{5}identifier{0}
+
+{1}; CPU instruction=6
+{6}add{0}
+
+{1}; math Instruction=7
+{7}fadd{0}
+
+{1}; register=8
+{8}ECX{0}
+
+{1}; directive=9
+{9}section{0}
+
+{1}; directive operand=10
+{10}rel{0}
+
+{1}; comment block=11 is for future expansion
+{0}
+{1}; character=12
+{12}'character'{0}
+
+{1}; string EOL=13
+{13}"no line end
+{0}
+{1}; extended instruction=14
+{14}movq{0}
+
+{1}; comment directive=15
+{0} {9}comment{0} {15}~ A multiple-line
+ comment directive~{0}
+
+{1};end
diff --git a/lexilla/test/examples/asm/SciTE.properties b/lexilla/test/examples/asm/SciTE.properties
new file mode 100644
index 000000000..8acf144e4
--- /dev/null
+++ b/lexilla/test/examples/asm/SciTE.properties
@@ -0,0 +1,9 @@
+lexer.*.asm=asm
+
+keywords.*.asm=add sub xor mov lea call
+keywords2.*.asm=fadd
+keywords3.*.asm=rsp rax rcx rdx r8 r9 ecx
+keywords4.*.asm=db section alignb resq resqdb global extern equ .bss .text .data start comment
+keywords5.*.asm=qword rel
+keywords6.*.asm=movd movq 
+
diff --git a/lexilla/test/examples/batch/Issue222.bat b/lexilla/test/examples/batch/Issue222.bat
new file mode 100644
index 000000000..9d7708009
--- /dev/null
+++ b/lexilla/test/examples/batch/Issue222.bat
@@ -0,0 +1,26 @@
+rem Keywords with colon
+
+rem with spacing
+call file.bat arg1
+call "file.bat" arg1
+call :label arg1
+goto :label
+goto :eof
+goto label
+echo: %var%
+echo: text
+echo text
+
+rem no spacing
+call:label arg1
+goto:label
+goto:eof
+echo:%var%
+echo:text
+(call)
+(echo:)
+(goto)
+
+rem call internal commands
+call echo text
+call set "a=b"
diff --git a/lexilla/test/examples/batch/Issue222.bat.folded b/lexilla/test/examples/batch/Issue222.bat.folded
new file mode 100644
index 000000000..bacd4ed24
--- /dev/null
+++ b/lexilla/test/examples/batch/Issue222.bat.folded
@@ -0,0 +1,27 @@
+ 0 400   0   rem Keywords with colon
+ 0 400   0   
+ 0 400   0   rem with spacing
+ 0 400   0   call file.bat arg1
+ 0 400   0   call "file.bat" arg1
+ 0 400   0   call :label arg1
+ 0 400   0   goto :label
+ 0 400   0   goto :eof
+ 0 400   0   goto label
+ 0 400   0   echo: %var%
+ 0 400   0   echo: text
+ 0 400   0   echo text
+ 0 400   0   
+ 0 400   0   rem no spacing
+ 0 400   0   call:label arg1
+ 0 400   0   goto:label
+ 0 400   0   goto:eof
+ 0 400   0   echo:%var%
+ 0 400   0   echo:text
+ 0 400   0   (call)
+ 0 400   0   (echo:)
+ 0 400   0   (goto)
+ 0 400   0   
+ 0 400   0   rem call internal commands
+ 0 400   0   call echo text
+ 0 400   0   call set "a=b"
+ 0 400   0   
\ No newline at end of file
diff --git a/lexilla/test/examples/batch/Issue222.bat.styled b/lexilla/test/examples/batch/Issue222.bat.styled
new file mode 100644
index 000000000..76a576907
--- /dev/null
+++ b/lexilla/test/examples/batch/Issue222.bat.styled
@@ -0,0 +1,26 @@
+{1}rem Keywords with colon
+{0}
+{1}rem with spacing
+{2}call{5} file.bat{0} arg1
+{2}call{0} "file.bat" arg1
+{2}call{0} :label arg1
+{2}goto{0} :label
+{2}goto{0} :eof
+{2}goto{0} label
+{2}echo{0}: {6}%var%{0}
+{2}echo{0}: text
+{2}echo{0} text
+
+{1}rem no spacing
+{2}call{0}:label arg1
+{2}goto{0}:label
+{2}goto{0}:eof
+{2}echo{0}:{6}%var%{0}
+{2}echo{0}:text
+({2}call{0})
+({2}echo{0}:)
+({2}goto{0})
+
+{1}rem call internal commands
+{2}call echo{0} text
+{2}call set{0} "a=b"
diff --git a/lexilla/test/examples/cpp/94Template.cxx b/lexilla/test/examples/cpp/94Template.cxx
new file mode 100644
index 000000000..f8c3d6e16
--- /dev/null
+++ b/lexilla/test/examples/cpp/94Template.cxx
@@ -0,0 +1,31 @@
+// Test JavaScript template expressions for issue 94
+
+// Basic
+var basic = `${identifier}`;
+
+// Nested
+var nested = ` ${ ` ${ 1 } ` } `;
+
+// With escapes
+var xxx = {
+    '1': `\`\u0020\${a${1 + 1}b}`,
+    '2': `\${a${ `b${1 + 2}c`.charCodeAt(2) }d}`,
+    '3': `\${a${ `b${ `c${ JSON.stringify({
+        '4': {},
+        }) }d` }e` }f}`,
+};
+
+// Original request
+fetchOptions.body = `
+{
+	"accountNumber" : "248796",
+	"customerType" : "Shipper",
+	"destinationCity" : "${order.destination.city}",
+	"destinationState" : "${order.destination.stateProvince}",
+	"destinationZip" : ${order.destination.postalCode},
+	"paymentType" : "Prepaid",
+	"shipmentInfo" :
+	{
+		"items" : [ { "shipmentClass" : "50", "shipmentWeight" : "${order.totalWeight.toString()}" } ]
+	}
+}`;
diff --git a/lexilla/test/examples/cpp/94Template.cxx.folded b/lexilla/test/examples/cpp/94Template.cxx.folded
new file mode 100644
index 000000000..57bf07022
--- /dev/null
+++ b/lexilla/test/examples/cpp/94Template.cxx.folded
@@ -0,0 +1,32 @@
+ 0 400 400   // Test JavaScript template expressions for issue 94
+ 1 400 400   
+ 0 400 400   // Basic
+ 0 400 400   var basic = `${identifier}`;
+ 1 400 400   
+ 0 400 400   // Nested
+ 0 400 400   var nested = ` ${ ` ${ 1 } ` } `;
+ 1 400 400   
+ 0 400 400   // With escapes
+ 2 400 401 + var xxx = {
+ 0 401 401 |     '1': `\`\u0020\${a${1 + 1}b}`,
+ 0 401 401 |     '2': `\${a${ `b${1 + 2}c`.charCodeAt(2) }d}`,
+ 2 401 406 +     '3': `\${a${ `b${ `c${ JSON.stringify({
+ 0 406 406 |         '4': {},
+ 0 406 401 |         }) }d` }e` }f}`,
+ 0 401 400 | };
+ 1 400 400   
+ 0 400 400   // Original request
+ 0 400 400   fetchOptions.body = `
+ 0 400 400   {
+ 0 400 400   	"accountNumber" : "248796",
+ 0 400 400   	"customerType" : "Shipper",
+ 0 400 400   	"destinationCity" : "${order.destination.city}",
+ 0 400 400   	"destinationState" : "${order.destination.stateProvince}",
+ 0 400 400   	"destinationZip" : ${order.destination.postalCode},
+ 0 400 400   	"paymentType" : "Prepaid",
+ 0 400 400   	"shipmentInfo" :
+ 0 400 400   	{
+ 0 400 400   		"items" : [ { "shipmentClass" : "50", "shipmentWeight" : "${order.totalWeight.toString()}" } ]
+ 0 400 400   	}
+ 0 400 400   }`;
+ 1 400 400   
\ No newline at end of file
diff --git a/lexilla/test/examples/cpp/94Template.cxx.styled b/lexilla/test/examples/cpp/94Template.cxx.styled
new file mode 100644
index 000000000..4023480e3
--- /dev/null
+++ b/lexilla/test/examples/cpp/94Template.cxx.styled
@@ -0,0 +1,31 @@
+{2}// Test JavaScript template expressions for issue 94
+{0}
+{2}// Basic
+{5}var{0} {11}basic{0} {10}={0} {20}`{10}${{11}identifier{10}}{20}`{10};{0}
+
+{2}// Nested
+{5}var{0} {11}nested{0} {10}={0} {20}` {10}${{0} {20}` {10}${{0} {4}1{0} {10}}{20} `{0} {10}}{20} `{10};{0}
+
+{2}// With escapes
+{5}var{0} {11}xxx{0} {10}={0} {10}{{0}
+    {7}'1'{10}:{0} {20}`{27}\`\u0020\${20}{a{10}${{4}1{0} {10}+{0} {4}1{10}}{20}b}`{10},{0}
+    {7}'2'{10}:{0} {20}`{27}\${20}{a{10}${{0} {20}`b{10}${{4}1{0} {10}+{0} {4}2{10}}{20}c`{10}.{16}charCodeAt{10}({4}2{10}){0} {10}}{20}d}`{10},{0}
+    {7}'3'{10}:{0} {20}`{27}\${20}{a{10}${{0} {20}`b{10}${{0} {20}`c{10}${{0} {19}JSON{10}.{16}stringify{10}({{0}
+        {7}'4'{10}:{0} {10}{},{0}
+        {10}}){0} {10}}{20}d`{0} {10}}{20}e`{0} {10}}{20}f}`{10},{0}
+{10}};{0}
+
+{2}// Original request
+{11}fetchOptions{10}.{11}body{0} {10}={0} {20}`
+{
+	"accountNumber" : "248796",
+	"customerType" : "Shipper",
+	"destinationCity" : "{10}${{11}order{10}.{11}destination{10}.{11}city{10}}{20}",
+	"destinationState" : "{10}${{11}order{10}.{11}destination{10}.{11}stateProvince{10}}{20}",
+	"destinationZip" : {10}${{11}order{10}.{11}destination{10}.{11}postalCode{10}}{20},
+	"paymentType" : "Prepaid",
+	"shipmentInfo" :
+	{
+		"items" : [ { "shipmentClass" : "50", "shipmentWeight" : "{10}${{11}order{10}.{11}totalWeight{10}.{11}toString{10}()}{20}" } ]
+	}
+}`{10};{0}
diff --git a/lexilla/test/examples/cpp/SciTE.properties b/lexilla/test/examples/cpp/SciTE.properties
index 8429e1eed..217c79e95 100644
--- a/lexilla/test/examples/cpp/SciTE.properties
+++ b/lexilla/test/examples/cpp/SciTE.properties
@@ -1,9 +1,9 @@
 # coding: utf-8
 lexer.*.cxx=cpp
-keywords.*.cxx=int let uuid
-keywords2.*.cxx=second Upper
+keywords.*.cxx=int let uuid var
+keywords2.*.cxx=charCodeAt second stringify Upper
 keywords3.*.cxx=file
-keywords4.*.cxx=global
+keywords4.*.cxx=global JSON
 keywords5.*.cxx=
 keywords6.*.cxx=TODO
 
@@ -20,6 +20,7 @@ lexer.cpp.escape.sequence=1
 styling.within.preprocessor=0
 lexer.cpp.triplequoted.strings=1
 lexer.cpp.hashquoted.strings=1
+lexer.cpp.backquoted.strings=2
 
 fold=1
 fold.preprocessor=1
diff --git a/lexilla/test/examples/fortran/AllStyles.f b/lexilla/test/examples/fortran/AllStyles.f
new file mode 100644
index 000000000..23a180ddc
--- /dev/null
+++ b/lexilla/test/examples/fortran/AllStyles.f
@@ -0,0 +1,47 @@
+! Enumerate all styles: 0 to 14
+! This is not a viable source file, it just illustrates the different states in isolation.
+
+! comment=1
+! Comment
+
+! default=0
+	! w
+
+! number=2
+.37
+
+! string1=3
+'string'
+
+! string2=4
+"string"
+
+! stringeol=5
+" unclosed
+
+! operator=6
++
+
+! identifier=7
+variable
+
+! word=8
+program
+
+! word2=9
+system_clock
+
+! word3=10
+doublecomplex
+
+! preprocessor=11
+!DEC$ ATTRIBUTES DLLEXPORT::sr1
+
+! operator2=12
+.lt.
+
+! label=13
+999
+
+! continuation=14
+&
diff --git a/lexilla/test/examples/fortran/AllStyles.f.folded b/lexilla/test/examples/fortran/AllStyles.f.folded
new file mode 100644
index 000000000..7e2f0c5b0
--- /dev/null
+++ b/lexilla/test/examples/fortran/AllStyles.f.folded
@@ -0,0 +1,48 @@
+ 0 400   0   ! Enumerate all styles: 0 to 14
+ 0 400   0   ! This is not a viable source file, it just illustrates the different states in isolation.
+ 1 400   0   
+ 0 400   0   ! comment=1
+ 0 400   0   ! Comment
+ 1 400   0   
+ 0 400   0   ! default=0
+ 0 400   0   	! w
+ 1 400   0   
+ 0 400   0   ! number=2
+ 0 400   0   .37
+ 1 400   0   
+ 0 400   0   ! string1=3
+ 0 400   0   'string'
+ 1 400   0   
+ 0 400   0   ! string2=4
+ 0 400   0   "string"
+ 1 400   0   
+ 0 400   0   ! stringeol=5
+ 0 400   0   " unclosed
+ 1 400   0   
+ 0 400   0   ! operator=6
+ 0 400   0   +
+ 1 400   0   
+ 0 400   0   ! identifier=7
+ 0 400   0   variable
+ 1 400   0   
+ 0 400   0   ! word=8
+ 2 400   0 + program
+ 1 401   0 | 
+ 0 401   0 | ! word2=9
+ 0 401   0 | system_clock
+ 1 401   0 | 
+ 0 401   0 | ! word3=10
+ 0 401   0 | doublecomplex
+ 1 401   0 | 
+ 0 401   0 | ! preprocessor=11
+ 0 401   0 | !DEC$ ATTRIBUTES DLLEXPORT::sr1
+ 1 401   0 | 
+ 0 401   0 | ! operator2=12
+ 0 401   0 | .lt.
+ 1 401   0 | 
+ 0 401   0 | ! label=13
+ 0 401   0 | 999
+ 1 401   0 | 
+ 0 401   0 | ! continuation=14
+ 0 401   0 | &
+ 0 400   0   
\ No newline at end of file
diff --git a/lexilla/test/examples/fortran/AllStyles.f.styled b/lexilla/test/examples/fortran/AllStyles.f.styled
new file mode 100644
index 000000000..f76cc1a01
--- /dev/null
+++ b/lexilla/test/examples/fortran/AllStyles.f.styled
@@ -0,0 +1,47 @@
+{1}! Enumerate all styles: 0 to 14{0}
+{1}! This is not a viable source file, it just illustrates the different states in isolation.{0}
+
+{1}! comment=1{0}
+{1}! Comment{0}
+
+{1}! default=0{0}
+	{1}! w{0}
+
+{1}! number=2{0}
+{2}.37{0}
+
+{1}! string1=3{0}
+{3}'string'{0}
+
+{1}! string2=4{0}
+{4}"string"{0}
+
+{1}! stringeol=5{0}
+{5}" unclosed
+{0}
+{1}! operator=6{0}
+{6}+{0}
+
+{1}! identifier=7{0}
+{7}variable{0}
+
+{1}! word=8{0}
+{8}program{0}
+
+{1}! word2=9{0}
+{9}system_clock{0}
+
+{1}! word3=10{0}
+{10}doublecomplex{0}
+
+{1}! preprocessor=11{0}
+{11}!DEC$ ATTRIBUTES DLLEXPORT::sr1{0}
+
+{1}! operator2=12{0}
+{12}.lt.{0}
+
+{1}! label=13{0}
+{13}999{0}
+
+{1}! continuation=14{0}
+{14}&{0}
diff --git a/lexilla/test/examples/fortran/SciTE.properties b/lexilla/test/examples/fortran/SciTE.properties
new file mode 100644
index 000000000..10afbb03b
--- /dev/null
+++ b/lexilla/test/examples/fortran/SciTE.properties
@@ -0,0 +1,6 @@
+lexer.*.f=fortran
+keywords.*.f=do end if program
+keywords2.*.f=system_clock
+keywords3.*.f=doublecomplex
+fold=1
+fold.compact=1
diff --git a/lexilla/test/examples/matlab/FoldPoints.m.matlab b/lexilla/test/examples/matlab/FoldPoints.m.matlab
index 7fb866eb5..10dc369c7 100644
--- a/lexilla/test/examples/matlab/FoldPoints.m.matlab
+++ b/lexilla/test/examples/matlab/FoldPoints.m.matlab
@@ -1,4 +1,4 @@
-% All the exaples here should yeild folding
+% All the examples here should yield folding
 
 classdef
     % Some code
diff --git a/lexilla/test/examples/matlab/FoldPoints.m.matlab.folded b/lexilla/test/examples/matlab/FoldPoints.m.matlab.folded
index 484daf05b..73751d911 100644
--- a/lexilla/test/examples/matlab/FoldPoints.m.matlab.folded
+++ b/lexilla/test/examples/matlab/FoldPoints.m.matlab.folded
@@ -1,4 +1,4 @@
- 0 400 400   % All the exaples here should yeild folding
+ 0 400 400   % All the examples here should yield folding
  1 400 400   
  2 400 401 + classdef
  0 401 401 |     % Some code
diff --git a/lexilla/test/examples/matlab/FoldPoints.m.matlab.styled b/lexilla/test/examples/matlab/FoldPoints.m.matlab.styled
index 9b9593af8..b4aa64af0 100644
--- a/lexilla/test/examples/matlab/FoldPoints.m.matlab.styled
+++ b/lexilla/test/examples/matlab/FoldPoints.m.matlab.styled
@@ -1,4 +1,4 @@
-{1}% All the exaples here should yeild folding{0}
+{1}% All the examples here should yield folding{0}
 
 {4}classdef{0}
     {1}% Some code{0}
diff --git a/lexilla/test/examples/mysql/AllStyles.sql b/lexilla/test/examples/mysql/AllStyles.sql
new file mode 100644
index 000000000..e7369eb96
--- /dev/null
+++ b/lexilla/test/examples/mysql/AllStyles.sql
@@ -0,0 +1,70 @@
+-- Enumerate all styles: 0 to 22, except for 3 (variable) and 11 (string) which are not implemented
+-- Hidden commands with other states (ored with ox40) are also possible inside /*! ... */
+
+/* commentline=2 */
+# comment
+
+# default=0
+	# w
+
+# comment=1
+/* comment */
+
+# variable=3 is not implemented
+@variable
+
+# systemvariable=4
+@@systemvariable
+
+# knownsystemvariable=5
+@@known
+
+# number=6
+6
+
+# majorkeyword=7
+select
+
+# keyword=8
+in
+
+# databaseobject=9
+object
+
+# procedurekeyword=10
+procedure
+
+# string=11 is not implemented
+
+# sqstring=12
+'string'
+
+# dqstring=13
+"string"
+
+# operator=14
++
+
+# function=15
+function()
+
+# identifier=16
+identifier
+
+# quotedidentifier=17
+`quoted`
+
+# user1=18
+user1
+
+# user2=19
+user2
+
+# user3=20
+user3
+
+# hiddencommand=21
+/*!*/
+
+# placeholder=22
+<{placeholder>}
diff --git a/lexilla/test/examples/mysql/AllStyles.sql.folded b/lexilla/test/examples/mysql/AllStyles.sql.folded
new file mode 100644
index 000000000..840734a9b
--- /dev/null
+++ b/lexilla/test/examples/mysql/AllStyles.sql.folded
@@ -0,0 +1,71 @@
+ 0 400 400   -- Enumerate all styles: 0 to 22, except for 3 (variable) and 11 (string) which are not implemented
+ 0 400 400   -- Hidden commands with other states (ored with ox40) are also possible inside /*! ... */
+ 1 400 400   
+ 0 400 400   /* commentline=2 */
+ 0 400 400   # comment
+ 1 400 400   
+ 0 400 400   # default=0
+ 0 400 400   	# w
+ 1 400 400   
+ 0 400 400   # comment=1
+ 0 400 400   /* comment */
+ 1 400 400   
+ 0 400 400   # variable=3 is not implemented
+ 0 400 400   @variable
+ 1 400 400   
+ 0 400 400   # systemvariable=4
+ 0 400 400   @@systemvariable
+ 1 400 400   
+ 0 400 400   # knownsystemvariable=5
+ 0 400 400   @@known
+ 1 400 400   
+ 0 400 400   # number=6
+ 0 400 400   6
+ 1 400 400   
+ 0 400 400   # majorkeyword=7
+ 0 400 400   select
+ 1 400 400   
+ 0 400 400   # keyword=8
+ 0 400 400   in
+ 1 400 400   
+ 0 400 400   # databaseobject=9
+ 0 400 400   object
+ 1 400 400   
+ 0 400 400   # procedurekeyword=10
+ 0 400 400   procedure
+ 1 400 400   
+ 0 400 400   # string=11 is not implemented
+ 1 400 400   
+ 0 400 400   # sqstring=12
+ 0 400 400   'string'
+ 1 400 400   
+ 0 400 400   # dqstring=13
+ 0 400 400   "string"
+ 1 400 400   
+ 0 400 400   # operator=14
+ 0 400 400   +
+ 1 400 400   
+ 0 400 400   # function=15
+ 0 400 400   function()
+ 1 400 400   
+ 0 400 400   # identifier=16
+ 0 400 400   identifier
+ 1 400 400   
+ 0 400 400   # quotedidentifier=17
+ 0 400 400   `quoted`
+ 1 400 400   
+ 0 400 400   # user1=18
+ 0 400 400   user1
+ 1 400 400   
+ 0 400 400   # user2=19
+ 0 400 400   user2
+ 1 400 400   
+ 0 400 400   # user3=20
+ 0 400 400   user3
+ 1 400 400   
+ 0 400 400   # hiddencommand=21
+ 0 400 400   /*!*/
+ 1 400 400   
+ 0 400 400   # placeholder=22
+ 0 400 400   <{placeholder>}
+ 0 400   0   
\ No newline at end of file
diff --git a/lexilla/test/examples/mysql/AllStyles.sql.styled b/lexilla/test/examples/mysql/AllStyles.sql.styled
new file mode 100644
index 000000000..ec0205481
--- /dev/null
+++ b/lexilla/test/examples/mysql/AllStyles.sql.styled
@@ -0,0 +1,70 @@
+{2}-- Enumerate all styles: 0 to 22, except for 3 (variable) and 11 (string) which are not implemented
+-- Hidden commands with other states (ored with ox40) are also possible inside /*! ... */
+{0}
+{1}/* commentline=2 */{0}
+{2}# comment
+{0}
+{2}# default=0
+{0}	{2}# w
+{0}
+{2}# comment=1
+{1}/* comment */{0}
+
+{2}# variable=3 is not implemented
+{14}@{16}variable{0}
+
+{2}# systemvariable=4
+{4}@@systemvariable{0}
+
+{2}# knownsystemvariable=5
+{5}@@known{0}
+
+{2}# number=6
+{6}6{0}
+
+{2}# majorkeyword=7
+{7}select{0}
+
+{2}# keyword=8
+{8}in{0}
+
+{2}# databaseobject=9
+{9}object{0}
+
+{2}# procedurekeyword=10
+{10}procedure{0}
+
+{2}# string=11 is not implemented
+{0}
+{2}# sqstring=12
+{12}'string'{0}
+
+{2}# dqstring=13
+{13}"string"{0}
+
+{2}# operator=14
+{14}+{0}
+
+{2}# function=15
+{15}function{14}(){0}
+
+{2}# identifier=16
+{16}identifier{0}
+
+{2}# quotedidentifier=17
+{17}`quoted`{0}
+
+{2}# user1=18
+{18}user1{0}
+
+{2}# user2=19
+{19}user2{0}
+
+{2}# user3=20
+{20}user3{0}
+
+{2}# hiddencommand=21
+{21}/*!*/{0}
+
+{2}# placeholder=22
+{22}<{placeholder>}
diff --git a/lexilla/test/examples/mysql/SciTE.properties b/lexilla/test/examples/mysql/SciTE.properties
new file mode 100644
index 000000000..f6ee78114
--- /dev/null
+++ b/lexilla/test/examples/mysql/SciTE.properties
@@ -0,0 +1,18 @@
+lexer.*.sql=mysql
+
+keywords.*.sql=select
+keywords2.*.sql=in
+keywords3.*.sql=object
+keywords4.*.sql=function
+keywords5.*.sql=known
+keywords6.*.sql=procedure
+keywords7.*.sql=user1
+keywords8.*.sql=user2
+keywords9.*.sql=user3
+
+lexer.sql.backticks.identifier=1
+lexer.sql.numbersign.comment=1
+lexer.sql.allow.dotted.word=1
+
+fold=1
+fold.compact=1
diff --git a/lexilla/test/examples/python/strings.py b/lexilla/test/examples/python/strings.py
new file mode 100644
index 000000000..8576cb9d1
--- /dev/null
+++ b/lexilla/test/examples/python/strings.py
@@ -0,0 +1,16 @@
+# Simple raw string
+r''
+
+# Raw f-string
+rf''
+fr''
+
+# Raw byte string
+rb''
+br''
+
+# Raw unicode strings: ur'' is valid in 2.7 (but not in 3) -- always lexed as
+# valid; ru'' is never valid
+ru''
+ur''
+
diff --git a/lexilla/test/examples/python/strings.py.folded b/lexilla/test/examples/python/strings.py.folded
new file mode 100644
index 000000000..994f9609b
--- /dev/null
+++ b/lexilla/test/examples/python/strings.py.folded
@@ -0,0 +1,17 @@
+ 0 400   0   # Simple raw string
+ 0 400   0   r''
+ 1 400   0   
+ 0 400   0   # Raw f-string
+ 0 400   0   rf''
+ 0 400   0   fr''
+ 1 400   0   
+ 0 400   0   # Raw byte string
+ 0 400   0   rb''
+ 0 400   0   br''
+ 1 400   0   
+ 0 400   0   # Raw unicode strings: ur'' is valid in 2.7 (but not in 3) -- always lexed as
+ 0 400   0   # valid; ru'' is never valid
+ 0 400   0   ru''
+ 0 400   0   ur''
+ 1 400   0   
+ 1 400   0   
\ No newline at end of file
diff --git a/lexilla/test/examples/python/strings.py.styled b/lexilla/test/examples/python/strings.py.styled
new file mode 100644
index 000000000..5b5d3cc61
--- /dev/null
+++ b/lexilla/test/examples/python/strings.py.styled
@@ -0,0 +1,16 @@
+{1}# Simple raw string{0}
+{4}r''{0}
+
+{1}# Raw f-string{0}
+{17}rf''{0}
+{17}fr''{0}
+
+{1}# Raw byte string{0}
+{4}rb''{0}
+{4}br''{0}
+
+{1}# Raw unicode strings: ur'' is valid in 2.7 (but not in 3) -- always lexed as{0}
+{1}# valid; ru'' is never valid{0}
+{11}ru{4}''{0}
+{4}ur''{0}
+
diff --git a/lexilla/test/examples/ruby/225NumberDotMethod.rb b/lexilla/test/examples/ruby/225NumberDotMethod.rb
new file mode 100644
index 000000000..97c4c43b9
--- /dev/null
+++ b/lexilla/test/examples/ruby/225NumberDotMethod.rb
@@ -0,0 +1,12 @@
+# Float Literals
+12.34
+1234e-2
+1.234E1
+# Range Literals
+(1..2)
+(2.0..3)
+# Method on number
+1.5.ceil
+1ri.abs
+3.times {|i| puts i}
+3. times {|i| puts i}
diff --git a/lexilla/test/examples/ruby/225NumberDotMethod.rb.folded b/lexilla/test/examples/ruby/225NumberDotMethod.rb.folded
new file mode 100644
index 000000000..6f2420867
--- /dev/null
+++ b/lexilla/test/examples/ruby/225NumberDotMethod.rb.folded
@@ -0,0 +1,13 @@
+ 0 400   0   # Float Literals
+ 0 400   0   12.34
+ 0 400   0   1234e-2
+ 0 400   0   1.234E1
+ 0 400   0   # Range Literals
+ 0 400   0   (1..2)
+ 0 400   0   (2.0..3)
+ 0 400   0   # Method on number
+ 0 400   0   1.5.ceil
+ 0 400   0   1ri.abs
+ 0 400   0   3.times {|i| puts i}
+ 0 400   0   3. times {|i| puts i}
+ 0 400   0   
\ No newline at end of file
diff --git a/lexilla/test/examples/ruby/225NumberDotMethod.rb.styled b/lexilla/test/examples/ruby/225NumberDotMethod.rb.styled
new file mode 100644
index 000000000..b1ecf323b
--- /dev/null
+++ b/lexilla/test/examples/ruby/225NumberDotMethod.rb.styled
@@ -0,0 +1,12 @@
+{2}# Float Literals{0}
+{4}12.34{0}
+{4}1234e{10}-{4}2{0}
+{4}1.234E1{0}
+{2}# Range Literals{0}
+{10}({4}1{10}..{4}2{10}){0}
+{10}({4}2.0{10}..{4}3{10}){0}
+{2}# Method on number{0}
+{4}1.5{10}.{11}ceil{0}
+{4}1ri{10}.{11}abs{0}
+{4}3{10}.{11}times{0} {10}{|{11}i{10}|{0} {11}puts{0} {11}i{10}}{0}
+{4}3{10}.{0} {11}times{0} {10}{|{11}i{10}|{0} {11}puts{0} {11}i{10}}{0}
diff --git a/lexilla/test/examples/sql/AllStyles.sql b/lexilla/test/examples/sql/AllStyles.sql
new file mode 100644
index 000000000..d8121d1eb
--- /dev/null
+++ b/lexilla/test/examples/sql/AllStyles.sql
@@ -0,0 +1,70 @@
+-- Enumerate all styles: 0 to 24
+
+-- comment=1
+/* comment */
+
+-- whitespace=0
+	-- w
+
+/* commentline=2 */
+-- commentline
+
+-- commentdoc=3
+/** commentdoc */
+
+-- number=4
+4
+
+-- word=5
+select
+
+-- string=6
+"string"
+
+-- character=7
+'character'
+
+-- sqlplus=8
+append
+
+-- sqlplus_prompt=9
+prompt SQL+Prompt
+
+-- operator=10
++
+
+-- identifier=11
+identifier
+
+-- sqlplus_comment=13
+remark sqlplus comment
+
+-- commentlinedoc=15
+# commentlinedoc
+
+-- word2=16
+object
+
+-- commentdockeyword=17
+/** @return */
+
+-- commentdockeyworderror=18
+/** @error */
+
+-- user1=19
+dbms_output.disable
+
+-- user2=20
+analyze
+
+-- user3=21
+array
+
+-- user4=22
+false
+
+-- quotedidentifier=23
+`quotedidentifier`
+
+-- qoperator=24
+q'{ today's }'
diff --git a/lexilla/test/examples/sql/AllStyles.sql.folded b/lexilla/test/examples/sql/AllStyles.sql.folded
new file mode 100644
index 000000000..53b15868a
--- /dev/null
+++ b/lexilla/test/examples/sql/AllStyles.sql.folded
@@ -0,0 +1,71 @@
+ 0 400 400   -- Enumerate all styles: 0 to 24
+ 1 400 400   
+ 0 400 400   -- comment=1
+ 0 400 400   /* comment */
+ 1 400 400   
+ 0 400 400   -- whitespace=0
+ 0 400 400   	-- w
+ 1 400 400   
+ 0 400 400   /* commentline=2 */
+ 0 400 400   -- commentline
+ 1 400 400   
+ 0 400 400   -- commentdoc=3
+ 0 400 400   /** commentdoc */
+ 1 400 400   
+ 0 400 400   -- number=4
+ 0 400 400   4
+ 1 400 400   
+ 0 400 400   -- word=5
+ 0 400 400   select
+ 1 400 400   
+ 0 400 400   -- string=6
+ 0 400 400   "string"
+ 1 400 400   
+ 0 400 400   -- character=7
+ 0 400 400   'character'
+ 1 400 400   
+ 0 400 400   -- sqlplus=8
+ 0 400 400   append
+ 1 400 400   
+ 0 400 400   -- sqlplus_prompt=9
+ 0 400 400   prompt SQL+Prompt
+ 1 400 400   
+ 0 400 400   -- operator=10
+ 0 400 400   +
+ 1 400 400   
+ 0 400 400   -- identifier=11
+ 0 400 400   identifier
+ 1 400 400   
+ 0 400 400   -- sqlplus_comment=13
+ 0 400 400   remark sqlplus comment
+ 1 400 400   
+ 0 400 400   -- commentlinedoc=15
+ 0 400 400   # commentlinedoc
+ 1 400 400   
+ 0 400 400   -- word2=16
+ 0 400 400   object
+ 1 400 400   
+ 0 400 400   -- commentdockeyword=17
+ 0 400 400   /** @return */
+ 1 400 400   
+ 0 400 400   -- commentdockeyworderror=18
+ 0 400 400   /** @error */
+ 1 400 400   
+ 0 400 400   -- user1=19
+ 0 400 400   dbms_output.disable
+ 1 400 400   
+ 0 400 400   -- user2=20
+ 0 400 400   analyze
+ 1 400 400   
+ 0 400 400   -- user3=21
+ 0 400 400   array
+ 1 400 400   
+ 0 400 400   -- user4=22
+ 0 400 400   false
+ 1 400 400   
+ 0 400 400   -- quotedidentifier=23
+ 0 400 400   `quotedidentifier`
+ 1 400 400   
+ 0 400 400   -- qoperator=24
+ 0 400 400   q'{ today's }'
+ 0 400   0   
\ No newline at end of file
diff --git a/lexilla/test/examples/sql/AllStyles.sql.styled b/lexilla/test/examples/sql/AllStyles.sql.styled
new file mode 100644
index 000000000..35b4334da
--- /dev/null
+++ b/lexilla/test/examples/sql/AllStyles.sql.styled
@@ -0,0 +1,70 @@
+{2}-- Enumerate all styles: 0 to 24
+{0}
+{2}-- comment=1
+{1}/* comment */{0}
+
+{2}-- whitespace=0
+{0}	{2}-- w
+{0}
+{1}/* commentline=2 */{0}
+{2}-- commentline
+{0}
+{2}-- commentdoc=3
+{3}/** commentdoc */{0}
+
+{2}-- number=4
+{4}4{0}
+
+{2}-- word=5
+{5}select{0}
+
+{2}-- string=6
+{6}"string"{0}
+
+{2}-- character=7
+{7}'character'{0}
+
+{2}-- sqlplus=8
+{8}append{0}
+
+{2}-- sqlplus_prompt=9
+{8}prompt{9} SQL+Prompt
+{0}
+{2}-- operator=10
+{10}+{0}
+
+{2}-- identifier=11
+{11}identifier{0}
+
+{2}-- sqlplus_comment=13
+{8}remark{13} sqlplus comment
+{0}
+{2}-- commentlinedoc=15
+{15}# commentlinedoc
+{0}
+{2}-- word2=16
+{16}object{0}
+
+{2}-- commentdockeyword=17
+{3}/** {17}@return{3} */{0}
+
+{2}-- commentdockeyworderror=18
+{3}/** {18}@error{3} */{0}
+
+{2}-- user1=19
+{19}dbms_output.disable{0}
+
+{2}-- user2=20
+{20}analyze{0}
+
+{2}-- user3=21
+{21}array{0}
+
+{2}-- user4=22
+{22}false{0}
+
+{2}-- quotedidentifier=23
+{23}`quotedidentifier`{0}
+
+{2}-- qoperator=24
+{24}q'{ today's }'{0}
diff --git a/lexilla/test/examples/sql/SciTE.properties b/lexilla/test/examples/sql/SciTE.properties
new file mode 100644
index 000000000..e3bc62c90
--- /dev/null
+++ b/lexilla/test/examples/sql/SciTE.properties
@@ -0,0 +1,17 @@
+lexer.*.sql=sql
+
+keywords.*.sql=select
+keywords2.*.sql=object
+keywords3.*.sql=return
+keywords4.*.sql=a~ppend pro~mpt rem~ark
+keywords5.*.sql=dbms_output.disable
+keywords6.*.sql=analyze
+keywords7.*.sql=array
+keywords8.*.sql=false
+
+lexer.sql.backticks.identifier=1
+lexer.sql.numbersign.comment=1
+lexer.sql.allow.dotted.word=1
+
+fold=1
+fold.compact=1
diff --git a/lexilla/test/unit/UnitTester.vcxproj b/lexilla/test/unit/UnitTester.vcxproj
index 48df9678a..97b14b54d 100644
--- a/lexilla/test/unit/UnitTester.vcxproj
+++ b/lexilla/test/unit/UnitTester.vcxproj
@@ -152,6 +152,7 @@
   <ItemGroup>
     <ClCompile Include="..\..\lexlib\Accessor.cxx" />
     <ClCompile Include="..\..\lexlib\CharacterSet.cxx" />
+    <ClCompile Include="..\..\lexlib\InList.cxx" />
     <ClCompile Include="..\..\lexlib\LexerBase.cxx" />
     <ClCompile Include="..\..\lexlib\LexerModule.cxx" />
     <ClCompile Include="..\..\lexlib\LexerSimple.cxx" />
diff --git a/lexilla/test/unit/makefile b/lexilla/test/unit/makefile
index d8a194a8a..e893db631 100644
--- a/lexilla/test/unit/makefile
+++ b/lexilla/test/unit/makefile
@@ -54,6 +54,7 @@ TESTOBJ=$(TESTSRC:.cxx=.o)
 TESTEDOBJ=\
  Accessor.o \
  CharacterSet.o \
+ InList.o \
  LexerBase.o \
  LexerModule.o \
  LexerSimple.o \
diff --git a/lexilla/test/unit/test.mak b/lexilla/test/unit/test.mak
index 5e5165c6d..ef63efb93 100644
--- a/lexilla/test/unit/test.mak
+++ b/lexilla/test/unit/test.mak
@@ -14,6 +14,7 @@ TESTSRC=test*.cxx
 TESTEDSRC=\
  ../../lexlib/Accessor.cxx \
  ../../lexlib/CharacterSet.cxx \
+ ../../lexlib/InList.cxx \
  ../../lexlib/LexerBase.cxx \
  ../../lexlib/LexerModule.cxx \
  ../../lexlib/LexerSimple.cxx \
diff --git a/lexilla/test/unit/testCharacterSet.cxx b/lexilla/test/unit/testCharacterSet.cxx
index 2b85cde2b..009c95059 100644
--- a/lexilla/test/unit/testCharacterSet.cxx
+++ b/lexilla/test/unit/testCharacterSet.cxx
@@ -5,6 +5,8 @@
 #include <cstdlib>
 #include <cassert>
 
+#include <string_view>
+
 #include "CharacterSet.h"
 
 #include "catch.hpp"
@@ -138,4 +140,12 @@ TEST_CASE("Functions") {
 		REQUIRE(CompareNCaseInsensitive("aa", "A", 1) == 0);
 	}
 
-}
\ No newline at end of file
+	SECTION("EqualCaseInsensitive") {
+		REQUIRE(EqualCaseInsensitive(" ", " "));
+		REQUIRE(EqualCaseInsensitive("A", "A"));
+		REQUIRE(EqualCaseInsensitive("a", "A"));
+		REQUIRE(!EqualCaseInsensitive("b", "A"));
+		REQUIRE(!EqualCaseInsensitive("aa", "A"));
+		REQUIRE(!EqualCaseInsensitive("a", "AA"));
+	}
+}
diff --git a/lexilla/test/unit/testInList.cxx b/lexilla/test/unit/testInList.cxx
new file mode 100644
index 000000000..6aa5e361d
--- /dev/null
+++ b/lexilla/test/unit/testInList.cxx
@@ -0,0 +1,28 @@
+/** @file testInList.cxx
+ ** Unit Tests for Lexilla internal data structures
+ **/
+
+#include <cstdlib>
+#include <cassert>
+
+#include <string_view>
+#include <initializer_list>
+
+#include "InList.h"
+
+#include "catch.hpp"
+
+using namespace Lexilla;
+
+// Test InList.
+
+TEST_CASE("InList") {
+
+	SECTION("Basic") {
+		REQUIRE(InList("dog", {"cat", "dog", "frog"}));
+		REQUIRE(!InList("fly", {"cat", "dog", "frog"}));
+
+		REQUIRE(InListCaseInsensitive("DOG", {"cat", "dog", "frog"}));
+		REQUIRE(!InListCaseInsensitive("fly", {"cat", "dog", "frog"}));
+	}
+}
diff --git a/lexilla/version.txt b/lexilla/version.txt
index f520b6ed4..1bc902939 100644
--- a/lexilla/version.txt
+++ b/lexilla/version.txt
@@ -1 +1 @@
-530
\ No newline at end of file
+531
\ No newline at end of file
diff --git a/scintilla/call/ScintillaCall.cxx b/scintilla/call/ScintillaCall.cxx
index 98e1dbd3e..78100e774 100644
--- a/scintilla/call/ScintillaCall.cxx
+++ b/scintilla/call/ScintillaCall.cxx
@@ -799,6 +799,66 @@ void ScintillaCall::EndUndoAction() {
 	Call(Message::EndUndoAction);
 }
 
+int ScintillaCall::UndoActions() {
+	return static_cast<int>(Call(Message::GetUndoActions));
+}
+
+void ScintillaCall::SetUndoSavePoint(int action) {
+	Call(Message::SetUndoSavePoint, action);
+}
+
+int ScintillaCall::UndoSavePoint() {
+	return static_cast<int>(Call(Message::GetUndoSavePoint));
+}
+
+void ScintillaCall::SetUndoDetach(int action) {
+	Call(Message::SetUndoDetach, action);
+}
+
+int ScintillaCall::UndoDetach() {
+	return static_cast<int>(Call(Message::GetUndoDetach));
+}
+
+void ScintillaCall::SetUndoTentative(int action) {
+	Call(Message::SetUndoTentative, action);
+}
+
+int ScintillaCall::UndoTentative() {
+	return static_cast<int>(Call(Message::GetUndoTentative));
+}
+
+void ScintillaCall::SetUndoCurrent(int action) {
+	Call(Message::SetUndoCurrent, action);
+}
+
+int ScintillaCall::UndoCurrent() {
+	return static_cast<int>(Call(Message::GetUndoCurrent));
+}
+
+void ScintillaCall::PushUndoActionType(int type, Position pos) {
+	Call(Message::PushUndoActionType, type, pos);
+}
+
+void ScintillaCall::ChangeLastUndoActionText(Position length, const char *text) {
+	CallString(Message::ChangeLastUndoActionText, length, text);
+}
+
+int ScintillaCall::UndoActionType(int action) {
+	return static_cast<int>(Call(Message::GetUndoActionType, action));
+}
+
+Position ScintillaCall::UndoActionPosition(int action) {
+	return Call(Message::GetUndoActionPosition, action);
+}
+
+int ScintillaCall::UndoActionText(int action, char *text) {
+	return static_cast<int>(CallPointer(Message::GetUndoActionText, action, text));
+}
+
+std::string ScintillaCall::UndoActionText(int action) {
+	return CallReturnString(Message::GetUndoActionText, action);
+}
+
 void ScintillaCall::IndicSetStyle(int indicator, Scintilla::IndicatorStyle indicatorStyle) {
 	Call(Message::IndicSetStyle, indicator, static_cast<intptr_t>(indicatorStyle));
 }
diff --git a/scintilla/cocoa/Scintilla/Info.plist b/scintilla/cocoa/Scintilla/Info.plist
index 8f93ed0dd..c7533ddc3 100644
--- a/scintilla/cocoa/Scintilla/Info.plist
+++ b/scintilla/cocoa/Scintilla/Info.plist
@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>$(PRODUCT_BUNDLE_PACKAGE_TYPE)</string>
 	<key>CFBundleShortVersionString</key>
-	<string>5.4.1</string>
+	<string>5.4.2</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 	<key>NSHumanReadableCopyright</key>
diff --git a/scintilla/cocoa/Scintilla/Scintilla.xcodeproj/project.pbxproj b/scintilla/cocoa/Scintilla/Scintilla.xcodeproj/project.pbxproj
index 004756d74..c30155539 100644
--- a/scintilla/cocoa/Scintilla/Scintilla.xcodeproj/project.pbxproj
+++ b/scintilla/cocoa/Scintilla/Scintilla.xcodeproj/project.pbxproj
@@ -98,6 +98,8 @@
 		286F8EE0260448C300EC8D60 /* Geometry.h in Headers */ = {isa = PBXBuildFile; fileRef = 286F8EDD260448C300EC8D60 /* Geometry.h */; };
 		287F3C6A246F90240040E76F /* Cocoa.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 287F3C69246F90240040E76F /* Cocoa.framework */; };
 		287F3C6C246F90300040E76F /* QuartzCore.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 287F3C6B246F90300040E76F /* QuartzCore.framework */; };
+		28B962A52B6AF44F00ACCD96 /* UndoHistory.cxx in Sources */ = {isa = PBXBuildFile; fileRef = 28B962A32B6AF44F00ACCD96 /* UndoHistory.cxx */; };
+		28B962A62B6AF44F00ACCD96 /* UndoHistory.h in Headers */ = {isa = PBXBuildFile; fileRef = 28B962A42B6AF44F00ACCD96 /* UndoHistory.h */; };
 		28EA9CAE255894B4007710C4 /* CharacterCategoryMap.cxx in Sources */ = {isa = PBXBuildFile; fileRef = 28EA9CAA255894B4007710C4 /* CharacterCategoryMap.cxx */; };
 		28EA9CAF255894B4007710C4 /* CharacterType.cxx in Sources */ = {isa = PBXBuildFile; fileRef = 28EA9CAB255894B4007710C4 /* CharacterType.cxx */; };
 		28EA9CB0255894B4007710C4 /* CharacterCategoryMap.h in Headers */ = {isa = PBXBuildFile; fileRef = 28EA9CAC255894B4007710C4 /* CharacterCategoryMap.h */; };
@@ -199,6 +201,8 @@
 		287F3C69246F90240040E76F /* Cocoa.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Cocoa.framework; path = System/Library/Frameworks/Cocoa.framework; sourceTree = SDKROOT; };
 		287F3C6B246F90300040E76F /* QuartzCore.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = QuartzCore.framework; path = System/Library/Frameworks/QuartzCore.framework; sourceTree = SDKROOT; };
 		287F3E0F246F9AE50040E76F /* module.modulemap */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = "sourcecode.module-map"; path = module.modulemap; sourceTree = SOURCE_ROOT; };
+		28B962A32B6AF44F00ACCD96 /* UndoHistory.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = UndoHistory.cxx; path = ../../src/UndoHistory.cxx; sourceTree = "<group>"; };
+		28B962A42B6AF44F00ACCD96 /* UndoHistory.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = UndoHistory.h; path = ../../src/UndoHistory.h; sourceTree = "<group>"; };
 		28EA9CAA255894B4007710C4 /* CharacterCategoryMap.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = CharacterCategoryMap.cxx; path = ../../src/CharacterCategoryMap.cxx; sourceTree = "<group>"; };
 		28EA9CAB255894B4007710C4 /* CharacterType.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = CharacterType.cxx; path = ../../src/CharacterType.cxx; sourceTree = "<group>"; };
 		28EA9CAC255894B4007710C4 /* CharacterCategoryMap.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = CharacterCategoryMap.h; path = ../../src/CharacterCategoryMap.h; sourceTree = "<group>"; };
@@ -306,6 +310,8 @@
 				2829372124E2D58700C84BA2 /* SplitVector.h */,
 				2829370424E2D58500C84BA2 /* Style.cxx */,
 				282936F224E2D58400C84BA2 /* Style.h */,
+				28B962A32B6AF44F00ACCD96 /* UndoHistory.cxx */,
+				28B962A42B6AF44F00ACCD96 /* UndoHistory.h */,
 				2829370F24E2D58500C84BA2 /* UniConversion.cxx */,
 				282936FC24E2D58400C84BA2 /* UniConversion.h */,
 				282936F324E2D58400C84BA2 /* UniqueString.cxx */,
@@ -397,6 +403,7 @@
 				2829376F24E2D58800C84BA2 /* Document.h in Headers */,
 				2829374A24E2D58800C84BA2 /* ContractionState.h in Headers */,
 				2829376024E2D58800C84BA2 /* XPM.h in Headers */,
+				28B962A62B6AF44F00ACCD96 /* UndoHistory.h in Headers */,
 				2829372F24E2D58800C84BA2 /* ElapsedPeriod.h in Headers */,
 				28EA9CB1255894B4007710C4 /* CharacterType.h in Headers */,
 				2829373A24E2D58800C84BA2 /* MarginView.h in Headers */,
@@ -522,6 +529,7 @@
 				2829373C24E2D58800C84BA2 /* CaseFolder.cxx in Sources */,
 				2829374824E2D58800C84BA2 /* RESearch.cxx in Sources */,
 				2829377024E2D58800C84BA2 /* EditView.cxx in Sources */,
+				28B962A52B6AF44F00ACCD96 /* UndoHistory.cxx in Sources */,
 				2829376724E2D58800C84BA2 /* ScintillaBase.cxx in Sources */,
 				2829374724E2D58800C84BA2 /* Style.cxx in Sources */,
 				2829375A24E2D58800C84BA2 /* ViewStyle.cxx in Sources */,
@@ -574,7 +582,7 @@
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
 				COPY_PHASE_STRIP = NO;
-				CURRENT_PROJECT_VERSION = 5.4.1;
+				CURRENT_PROJECT_VERSION = 5.4.2;
 				DEAD_CODE_STRIPPING = YES;
 				DEBUG_INFORMATION_FORMAT = dwarf;
 				ENABLE_STRICT_OBJC_MSGSEND = YES;
@@ -639,7 +647,7 @@
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
 				COPY_PHASE_STRIP = NO;
-				CURRENT_PROJECT_VERSION = 5.4.1;
+				CURRENT_PROJECT_VERSION = 5.4.2;
 				DEAD_CODE_STRIPPING = YES;
 				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
 				ENABLE_NS_ASSERTIONS = NO;
@@ -672,7 +680,7 @@
 				CODE_SIGN_IDENTITY = "-";
 				CODE_SIGN_STYLE = Manual;
 				COMBINE_HIDPI_IMAGES = YES;
-				CURRENT_PROJECT_VERSION = 5.4.1;
+				CURRENT_PROJECT_VERSION = 5.4.2;
 				DEAD_CODE_STRIPPING = YES;
 				DEFINES_MODULE = YES;
 				DEVELOPMENT_TEAM = "";
@@ -707,7 +715,7 @@
 				CODE_SIGN_IDENTITY = "-";
 				CODE_SIGN_STYLE = Manual;
 				COMBINE_HIDPI_IMAGES = YES;
-				CURRENT_PROJECT_VERSION = 5.4.1;
+				CURRENT_PROJECT_VERSION = 5.4.2;
 				DEAD_CODE_STRIPPING = YES;
 				DEFINES_MODULE = YES;
 				DEVELOPMENT_TEAM = "";
diff --git a/scintilla/cppcheck.suppress b/scintilla/cppcheck.suppress
index 15c44ac9a..5da17a6d0 100644
--- a/scintilla/cppcheck.suppress
+++ b/scintilla/cppcheck.suppress
@@ -27,12 +27,14 @@ constStatement:scintilla/src/Document.cxx
 // ILexer5* is not pointing at logically const
 constParameterPointer:scintilla/src/Document.cxx
 
+// Doesn't seem to understand that values change in loops
+knownConditionTrueFalse:scintilla/src/Document.cxx
+
 // Some non-explicit constructors are used for conversions or are private to lexers
 noExplicitConstructor
 
 // MarginView access to all bits is safe and is better defined in later versions of C++
 shiftTooManyBitsSigned:scintilla/src/MarginView.cxx
-integerOverflow:scintilla/src/MarginView.cxx
 
 // DLL entry points are unused inside Scintilla
 unusedFunction:scintilla/win32/ScintillaDLL.cxx
diff --git a/scintilla/doc/ScintillaDoc.html b/scintilla/doc/ScintillaDoc.html
index 66893e29b..e21536370 100644
--- a/scintilla/doc/ScintillaDoc.html
+++ b/scintilla/doc/ScintillaDoc.html
@@ -129,7 +129,7 @@
 
     <h1>Scintilla Documentation</h1>
 
-    <p>Last edited 19 December 2023 NH</p>
+    <p>Last edited 16 February 2024 NH</p>
 
     <p style="background:#90F0C0">Scintilla 5 has moved the lexers from Scintilla into a new
     <a href="Lexilla.html">Lexilla</a> project.<br />
@@ -341,97 +341,101 @@
 
         <tr>
           <td>&cir; <a class="toc" href="#UndoAndRedo">Undo and Redo</a></td>
+          <td>&cir; <a class="toc" href="#UndoSaveRestore">Undo save and restore</a></td>
           <td>&cir; <a class="toc" href="#ChangeHistory">Change history</a></td>
-          <td>&cir; <a class="toc" href="#ScrollingAndAutomaticScrolling">Scrolling and automatic scrolling</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#ScrollingAndAutomaticScrolling">Scrolling and automatic scrolling</a></td>
           <td>&cir; <a class="toc" href="#WhiteSpace">White space</a></td>
           <td>&cir; <a class="toc" href="#Cursor">Cursor</a></td>
-          <td>&cir; <a class="toc" href="#MouseCapture">Mouse capture</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#MouseCapture">Mouse capture</a></td>
           <td>&cir; <a class="toc" href="#LineEndings">Line endings</a></td>
           <td>&cir; <a class="toc" href="#Words">Words</a></td>
-          <td>&cir; <a class="toc" href="#Styling">Styling</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#Styling">Styling</a></td>
           <td>&cir; <a class="toc" href="#StyleDefinition">Style definition</a></td>
           <td>&cir; <a class="toc" href="#ElementColours">Element colours</a></td>
-          <td>&cir; <a class="toc" href="#CaretAndSelectionStyles">Selection, caret, and hotspot styles</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#CaretAndSelectionStyles">Selection, caret, and hotspot styles</a></td>
           <td>&cir; <a class="toc" href="#CharacterRepresentations">Character representations</a></td>
           <td>&cir; <a class="toc" href="#Margins">Margins</a></td>
-          <td>&cir; <a class="toc" href="#Annotations">Annotations</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#Annotations">Annotations</a></td>
           <td>&cir; <a class="toc" href="#EndOfLineAnnotations">End of Line Annotations</a></td>
           <td>&cir; <a class="toc" href="#OtherSettings">Other settings</a></td>
-          <td>&cir; <a class="toc" href="#BraceHighlighting">Brace highlighting</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#BraceHighlighting">Brace highlighting</a></td>
           <td>&cir; <a class="toc" href="#TabsAndIndentationGuides">Tabs and Indentation Guides</a></td>
           <td>&cir; <a class="toc" href="#Markers">Markers</a></td>
-          <td>&cir; <a class="toc" href="#Indicators">Indicators</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#Indicators">Indicators</a></td>
           <td>&cir; <a class="toc" href="#Autocompletion">Autocompletion</a></td>
           <td>&cir; <a class="toc" href="#UserLists">User lists</a></td>
-          <td>&cir; <a class="toc" href="#CallTips">Call tips</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#CallTips">Call tips</a></td>
           <td>&cir; <a class="toc" href="#KeyboardCommands">Keyboard commands</a></td>
           <td>&cir; <a class="toc" href="#KeyBindings">Key bindings</a></td>
-          <td>&cir; <a class="toc" href="#PopupEditMenu">Popup edit menu</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#PopupEditMenu">Popup edit menu</a></td>
           <td>&cir; <a class="toc" href="#MacroRecording">Macro recording</a></td>
           <td>&cir; <a class="toc" href="#Printing">Printing</a></td>
-          <td>&cir; <a class="toc" href="#DirectAccess">Direct access</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#DirectAccess">Direct access</a></td>
           <td>&cir; <a class="toc" href="#MultipleViews">Multiple views</a></td>
           <td>&cir; <a class="toc" href="#BackgroundLoadSave">Background loading and saving</a></td>
-          <td>&cir; <a class="toc" href="#DocumentInterface">Document interface</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#DocumentInterface">Document interface</a></td>
           <td>&cir; <a class="toc" href="#Folding">Folding</a></td>
           <td>&cir; <a class="toc" href="#LineWrapping">Line wrapping</a></td>
-          <td>&cir; <a class="toc" href="#Zooming">Zooming</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#Zooming">Zooming</a></td>
           <td>&cir; <a class="toc" href="#LongLines">Long lines</a></td>
           <td>&cir; <a class="toc" href="#Accessibility">Accessibility</a></td>
-          <td>&cir; <a class="toc" href="#Lexer">Lexer</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#Lexer">Lexer</a></td>
           <td>&cir; <a class="toc" href="#LexerObjects">Lexer objects</a></td>
           <td>&cir; <a class="toc" href="#Notifications">Notifications</a></td>
-          <td>&cir; <a class="toc" href="#Images">Images</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#Images">Images</a></td>
           <td>&cir; <a class="toc" href="#GTK">GTK</a></td>
           <td>&cir; <a class="toc" href="#ProvisionalMessages"><span class="provisional">Provisional messages</span></a></td>
-          <td>&cir; <a class="toc" href="#DeprecatedMessages">Deprecated messages</a></td>
         </tr>
 
         <tr>
+          <td>&cir; <a class="toc" href="#DeprecatedMessages">Deprecated messages</a></td>
           <td>&cir; <a class="toc" href="#EditMessagesNeverSupportedByScintilla">Edit messages never supported by Scintilla</a></td>
           <td>&cir; <a class="toc" href="#RemovedFeatures">Removed features</a></td>
+        </tr>
+
+        <tr>
           <td>&cir; <a class="toc" href="#BuildingScintilla">Building Scintilla</a></td>
         </tr>
       </tbody>
@@ -1988,6 +1992,117 @@ struct Sci_TextToFindFull {
      look like typing or deletions that look like multiple uses of the Backspace or Delete keys.
      </p>
 
+    <h2 id="UndoSaveRestore">Undo Save and Restore</h2>
+
+    <p>This feature is unfinished and has limitations.
+    When change history is active, it may show different changes than the previous session as undo actions
+    performed in that session are discarded in some circumstances such as when detaching from a save point.
+    A future version may add an API for archiving change history alongside undo history.
+    The operation sequences discussed here are a 'golden path' that has been tested to some extent and calling
+    the APIs in other circumstances or with out-of-bounds values may fail.</p>
+
+    <p>The behaviour of tentative actions in save and restore is uncertain as these are meant to be short-term states in language input
+    and which need to synchronize with a language IME (input method editor).
+    For now, restore the tentative point to -1 as it seems safest to regard the tentative change as committed.</p>
+
+    <p>Scintilla stores each change in an undo stack.
+    Various inter-action points play roles in undo behaviour: actions count, save point, detach point,
+    tentative point, and current action. Just like positions in documents, these points are between actions in the 
+    undo stack. Thus the current action specifies the number of actions that led to the current document state and
+    actions after this are for redo.
+    The save point specifies that the actions before this point are in the most recent save and actions after this are not yet saved.</p>
+    <p>When the user undoes from a save point and then performs a new change, the save point can no longer be reached and is -1.
+    The detach point is the point at which the undo stack branched away from the saved state and is used by
+    change history.</p>
+
+    <p>It is possible to retrieve the undo stack from Scintilla and subsequently restore the state of the stack.</p>
+
+    <p>An application may save both the document and its save stack between sessions to enable the user to return
+    to the same state the next time they edit.
+    For this to work, the loaded file must be exactly the same as when the undo stack was saved.
+    If the file was changed, even in minor ways like converting line ends from Windows to Unix style then
+    the undo actions will not line up so undo may fail completely and will produce unexpected results.</p>
+
+    <code><a class="message" href="#SCI_GETUNDOACTIONS">SCI_GETUNDOACTIONS &rarr; int</a><br />
+     <a class="message" href="#SCI_SETUNDOSAVEPOINT">SCI_SETUNDOSAVEPOINT(int action)</a><br />
+     <a class="message" href="#SCI_GETUNDOSAVEPOINT">SCI_GETUNDOSAVEPOINT &rarr; int</a><br />
+     <a class="message" href="#SCI_SETUNDODETACH">SCI_SETUNDODETACH(int action)</a><br />
+     <a class="message" href="#SCI_GETUNDODETACH">SCI_GETUNDODETACH &rarr; int</a><br />
+     <a class="message" href="#SCI_SETUNDOTENTATIVE">SCI_SETUNDOTENTATIVE(int action)</a><br />
+     <a class="message" href="#SCI_GETUNDOTENTATIVE">SCI_GETUNDOTENTATIVE &rarr; int</a><br />
+     <a class="message" href="#SCI_SETUNDOCURRENT">SCI_SETUNDOCURRENT(int action)</a><br />
+     <a class="message" href="#SCI_GETUNDOCURRENT">SCI_GETUNDOCURRENT &rarr; int</a><br />
+     <a class="message" href="#SCI_PUSHUNDOACTIONTYPE">SCI_PUSHUNDOACTIONTYPE(int type, position pos)</a><br />
+     <a class="message" href="#SCI_CHANGELASTUNDOACTIONTEXT">SCI_CHANGELASTUNDOACTIONTEXT(position length, const char *text)</a><br />
+     <a class="message" href="#SCI_GETUNDOACTIONTYPE">SCI_GETUNDOACTIONTYPE(int action) &rarr; int</a><br />
+     <a class="message" href="#SCI_GETUNDOACTIONPOSITION">SCI_GETUNDOACTIONPOSITION(int action) &rarr; position</a><br />
+     <a class="message" href="#SCI_GETUNDOACTIONTEXT ">SCI_GETUNDOACTIONTEXT(int action, char *text) &rarr; int</a><br />
+    </code>
+
+    <h3 id="UndoSave">Save</h3>
+
+    <p>The retrieval APIs are the 'GET*' ones:
+    <code>SCI_GETUNDOACTIONS</code>,
+    <code>SCI_GETUNDOSAVEPOINT</code>,
+    <code>SCI_GETUNDODETACH</code>,
+    <code>SCI_GETUNDOTENTATIVE</code>,
+    <code>SCI_GETUNDOCURRENT</code>,
+    <code>SCI_GETUNDOACTIONTYPE</code>,
+    <code>SCI_GETUNDOACTIONPOSITION</code>, and
+    <code>SCI_GETUNDOACTIONTEXT</code>.
+    </p>
+
+    <p>The <code>SCI_GETUNDOACTIONS</code>,
+    <code>SCI_GETUNDOSAVEPOINT</code>, <code>SCI_GETUNDODETACH</code>,
+    <code>SCI_GETUNDOTENTATIVE</code>, and <code>SCI_GETUNDOCURRENT</code>
+     APIs each return a single value and may be called in any order.
+    </p>
+
+    <p>The <code>SCI_GETUNDOACTIONTYPE</code>,
+    <code>SCI_GETUNDOACTIONPOSITION</code>, and <code>SCI_GETUNDOACTIONTEXT</code>
+    APIs take an action index and should be called with indices from 0 to one less than the result of
+    <code>SCI_GETUNDOACTIONS</code>.
+    The actions should only be iterated in the positive direction and should start from 0.
+    That is because undo stack data is not all randomly accessible and iterating in other orders may take O(n^2) time.
+    Data may also be inaccurate if a cursor is not initialised first with 0 index calls.
+    </p>
+
+    <h3 id="UndoRestore">Restore</h3>
+
+    <p>Restoration is only possible when the undo state is empty so <code>SCI_EMPTYUNDOBUFFER</code>
+    should be called first if there may already be some undo actions.</p>
+
+    <p>The restore APIs are the 'SET*' and others:
+    <code>SCI_SETUNDOSAVEPOINT</code>,
+    <code>SCI_SETUNDODETACH</code>,
+    <code>SCI_SETUNDOTENTATIVE</code>,
+    <code>SCI_SETUNDOCURRENT</code>,
+    <code>SCI_PUSHUNDOACTIONTYPE</code>, and
+    <code>SCI_CHANGELASTUNDOACTIONTEXT</code>.
+    </p>
+
+    <p>The history should first be set up with <code>SCI_PUSHUNDOACTIONTYPE</code> and
+    <code>SCI_CHANGELASTUNDOACTIONTEXT</code> then the save, detach, tentative, and current points set
+    with <code>SCI_SETUNDOSAVEPOINT</code>, <code>SCI_SETUNDODETACH</code>, <code>SCI_SETUNDOTENTATIVE</code>, and
+    <code>SCI_SETUNDOCURRENT</code>.
+    </p>
+
+    <p><code>SCI_PUSHUNDOACTIONTYPE(int type, position pos)</code> appends an action to the undo stack
+    with a particular type and position then the text and length of that action are set with
+    <code>SCI_CHANGELASTUNDOACTIONTEXT(position length, const char *text)</code>.
+    </p>
+
+    <p>
+    The last restoration API called should be <code>SCI_SETUNDOCURRENT</code> as this validates
+    the restored history and values against the document. For example, an undo history that could cause a negative
+    document length or insert / remove text outside the document is invalid.
+    If the restored undo state is invalid then a failure status is set and the undo history cleared.
+    Check for failure with <a class="seealso" href="#SCI_GETSTATUS">SCI_GETSTATUS</a>.
+    </p>
+
+    <p>The current implementation may only work when there is no tentative point.
+    </p>
+
     <h2 id="ChangeHistory">Change history</h2>
 
     <p>Scintilla can display document changes (modified, saved, ...) in the margin or in the text.</p>
diff --git a/scintilla/doc/ScintillaDownload.html b/scintilla/doc/ScintillaDownload.html
index a2018dd66..2ebe36f1a 100644
--- a/scintilla/doc/ScintillaDownload.html
+++ b/scintilla/doc/ScintillaDownload.html
@@ -26,9 +26,9 @@
     <table bgcolor="#CCCCCC" width="100%" cellspacing="0" cellpadding="8" border="0">
       <tr>
         <td>
-          <font size="4"> <a href="https://www.scintilla.org/scintilla541.zip">
+          <font size="4"> <a href="https://www.scintilla.org/scintilla542.zip">
 	Windows</a>&nbsp;&nbsp;
-	<a href="https://www.scintilla.org/scintilla541.tgz">
+	<a href="https://www.scintilla.org/scintilla542.tgz">
           GTK/Linux</a>&nbsp;&nbsp;
 	</font>
         </td>
@@ -42,7 +42,7 @@
       containing very few restrictions.
     </p>
     <h3>
-       Release 5.4.1
+       Release 5.4.2
     </h3>
     <h4>
        Source Code
@@ -50,8 +50,8 @@
        The source code package contains all of the source code for Scintilla but no binary
 	executable code and is available in
        <ul>
-       <li><a href="https://www.scintilla.org/scintilla541.zip">zip format</a> (1.8M) commonly used on Windows</li>
-       <li><a href="https://www.scintilla.org/scintilla541.tgz">tgz format</a> (1.6M) commonly used on Linux and compatible operating systems</li>
+       <li><a href="https://www.scintilla.org/scintilla542.zip">zip format</a> (1.8M) commonly used on Windows</li>
+       <li><a href="https://www.scintilla.org/scintilla542.tgz">tgz format</a> (1.7M) commonly used on Linux and compatible operating systems</li>
        </ul>
        Instructions for building on both Windows and Linux are included in the readme file.
     <h4>
diff --git a/scintilla/doc/ScintillaHistory.html b/scintilla/doc/ScintillaHistory.html
index 3510fe2e4..827ec6551 100644
--- a/scintilla/doc/ScintillaHistory.html
+++ b/scintilla/doc/ScintillaHistory.html
@@ -583,6 +583,39 @@
     </tr>
     </table>
     <h2>Releases</h2>
+    <h3>
+       <a href="https://www.scintilla.org/scintilla542.zip">Release 5.4.2</a>
+    </h3>
+    <ul>
+	<li>
+	Released 5 March 2024.
+	</li>
+	<li>
+	Significantly reduce memory used for undo actions, often to a half or quarter of previous versions.
+	<a href="https://sourceforge.net/p/scintilla/feature-requests/1458/">Feature #1458</a>.
+	</li>
+	<li>
+	Add APIs for saving and restoring undo history.
+	</li>
+	<li>
+	For GTK, when laying out text, detect runs with both left-to-right and right-to-left ranges and divide into an ASCII prefix and
+	more complex suffix. Lay out the ASCII prefix in the standard manner but, for the suffix, measure the whole width
+	and spread that over the suffix bytes. This produces more usable results where the caret moves over the ASCII prefix correctly
+	and over the suffix reasonably but not accurately.
+	</li>
+	<li>
+	For ScintillaEdit on Qt, fix reference from ScintillaDocument to Document to match change in 5.4.1
+	using IDocumentEditable for SCI_GETDOCPOINTER and SCI_SETDOCPOINTER.
+	</li>
+	<li>
+	For Direct2D on Win32, use the multi-threaded option to avoid crashes when Scintilla instances
+	created on different threads. There may be more problems with this scenario so it should be avoided.
+	<a href="https://sourceforge.net/p/scintilla/bugs/2420/">Bug #2420</a>.
+	</li>
+	<li>
+	For Win32, ensure keyboard-initiated context menu appears in multi-screen situations.
+	</li>
+    </ul>
     <h3>
        <a href="https://www.scintilla.org/scintilla541.zip">Release 5.4.1</a>
     </h3>
@@ -592,7 +625,7 @@
 	</li>
 	<li>
 	Add IDocumentEditable interface to allow efficient interaction with document objects which may not be visible in
-	a Scintilla instance. This feature is provisonal and may change before being declared stable.
+	a Scintilla instance. This feature is provisional and may change before being declared stable.
 	For better type-safety, the ScintillaCall C++ API uses IDocumentEditable* where void* was used before which may require
 	changes to client code that uses document pointer APIs
 	DocPointer, SetDocPointer, CreateDocument, AddRefDocument, and ReleaseDocument.
@@ -2024,7 +2057,7 @@
 	</li>
 	<li>
 	Add SCI_SETTABMINIMUMWIDTH to set the minimum width of tabs.
-	This allows minimaps or overviews to be layed out to match the full size editing view.
+	This allows minimaps or overviews to be laid out to match the full size editing view.
 	<a href="https://sourceforge.net/p/scintilla/bugs/2118/">Bug #2118</a>.
 	</li>
 	<li>
@@ -2593,7 +2626,7 @@
 	<a href="https://sourceforge.net/p/scintilla/feature-requests/1210/">Feature #1210.</a>
 	</li>
 	<li>
-	Fix hang in Lua lexer when lexing a label upto the terminating "::".
+	Fix hang in Lua lexer when lexing a label up to the terminating "::".
 	<a href="https://sourceforge.net/p/scintilla/bugs/1999/">Bug #1999</a>.
 	</li>
 	<li>
@@ -2820,7 +2853,7 @@
 	'Ctrl+L|SCI_LINEDELETE|'.
 	</li>
 	<li>
-	The Matlab lexer treats 'end' as a number rather than a keyword when used as a index.
+	The Matlab lexer treats 'end' as a number rather than a keyword when used as an index.
 	This also stops incorrect folding.
 	<a href="https://sourceforge.net/p/scintilla/bugs/1951/">Bug #1951</a>.
 	</li>
@@ -9863,7 +9896,7 @@
 	SciTE crashing bug fixed in incremental search on Windows ME.
 	</li>
 	<li>
-	SciTE on Windows has a optional find and replace dialogs that can search through
+	SciTE on Windows has an optional find and replace dialogs that can search through
 	all buffers and search within a particular style number.
 	</li>
     </ul>
@@ -11432,7 +11465,7 @@
 	SciTE's Export as LaTeX output improved.
       </li>
       <li>
-	Better choice of autocompletion displaying above the caret rather then
+	Better choice of autocompletion displaying above the caret rather than
 	below when that is more sensible.
       </li>
       <li>
@@ -14017,7 +14050,7 @@
       <li>
         Scintilla supports a 'savepoint' in the undo stack which can be set by the container when
         the document is saved. Notifications are sent to the container when the savepoint is
-        entered or left, allowing the container to to display a dirty indicator and change its
+        entered or left, allowing the container to display a dirty indicator and change its
         menus.
       </li>
       <li>
diff --git a/scintilla/doc/index.html b/scintilla/doc/index.html
index 492301cc0..565f88578 100644
--- a/scintilla/doc/index.html
+++ b/scintilla/doc/index.html
@@ -9,7 +9,7 @@
     <meta name="keywords" content="Scintilla, SciTE, Editing Component, Text Editor" />
     <meta name="Description"
     content="www.scintilla.org is the home of the Scintilla editing component and SciTE text editor application." />
-    <meta name="Date.Modified" content="20231227" />
+    <meta name="Date.Modified" content="20240305" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
     <style type="text/css">
         .logo {
@@ -60,8 +60,8 @@
           GTK, and macOS</font>
         </td>
         <td width="40%" align="right">
-          <font color="#FFCC99" size="3"> Release version 5.4.1<br />
-           Site last modified December 27 2023</font>
+          <font color="#FFCC99" size="3"> Release version 5.4.2<br />
+           Site last modified March 5 2024</font>
         </td>
         <td width="20%">
           &nbsp;
@@ -76,11 +76,11 @@
       </tr>
     </table>
     <ul id="versionlist">
+      <li>Version 5.4.2 can save and restore undo history.</li>
       <li>Version 5.4.1 adds IDocumentEditable interface to allow efficient interaction with document objects.</li>
       <li>Version 5.4.0 fixes crashes on macOS 12 and older when built with Xcode 15.0.</li>
       <li>Version 5.3.8 fixes excesssive memory use when deleting contiguous ranges backwards and is compatible with new macOS 14.</li>
       <li>Version 5.3.7 fixes platform-specific issues on GTK, Qt, and Win32.</li>
-      <li>Version 5.3.6 improves cursor behaviour on Win32 and IME support on Win32 and Qt.</li>
     </ul>
     <ul id="menu">
       <li id="remote1"><a href="https://www.scintilla.org/SciTEImage.html">Screenshot</a></li>
diff --git a/scintilla/gtk/PlatGTK.cxx b/scintilla/gtk/PlatGTK.cxx
index 3d7c6e765..2276c72b3 100644
--- a/scintilla/gtk/PlatGTK.cxx
+++ b/scintilla/gtk/PlatGTK.cxx
@@ -36,6 +36,7 @@
 
 #include "Scintilla.h"
 #include "ScintillaWidget.h"
+#include "CharacterType.h"
 #include "XPM.h"
 #include "UniConversion.h"
 
@@ -1085,6 +1086,27 @@ void SurfaceImpl::MeasureWidthsUTF8(const Font *font_, std::string_view text, XY
 		}
 		while (!iti.finished) {
 			iti.Next();
+			if (iti.curIndex < i) {
+				// Backwards movement indicater bidirectional.
+				// Divide into ASCII prefix and non-ASCII suffix as this is common case
+				// and produces accurate positions for the ASCII prefix.
+				size_t lenASCII=0;
+				while (lenASCII<text.length() && IsASCII(text[lenASCII])) {
+					lenASCII++;
+				}
+				const std::string_view asciiPrefix = text.substr(0, lenASCII);
+				const std::string_view bidiSuffix = text.substr(lenASCII);
+				// Recurse for ASCII prefix.
+				MeasureWidthsUTF8(font_, asciiPrefix, positions);
+				// Measure the whole bidiSuffix and spread its width evenly
+				const XYPOSITION endASCII = positions[lenASCII-1];
+				const XYPOSITION widthBidi = WidthText(font_, bidiSuffix);
+				const XYPOSITION widthByteBidi = widthBidi / bidiSuffix.length();
+				for (size_t bidiPos=0; bidiPos<bidiSuffix.length(); bidiPos++) {
+					positions[bidiPos+lenASCII] = endASCII + widthByteBidi * (bidiPos + 1);
+				}
+				return;
+			}
 			const int places = iti.curIndex - i;
 			while (i < iti.curIndex) {
 				// Evenly distribute space among bytes of this cluster.
diff --git a/scintilla/gtk/deps.mak b/scintilla/gtk/deps.mak
index 766bdaa0b..028f4a11d 100644
--- a/scintilla/gtk/deps.mak
+++ b/scintilla/gtk/deps.mak
@@ -9,6 +9,7 @@ PlatGTK.o: \
 	../include/Scintilla.h \
 	../include/Sci_Position.h \
 	../include/ScintillaWidget.h \
+	../src/CharacterType.h \
 	../src/XPM.h \
 	../src/UniConversion.h \
 	Wrappers.h \
@@ -142,6 +143,7 @@ CellBuffer.o: \
 	../src/SparseVector.h \
 	../src/ChangeHistory.h \
 	../src/CellBuffer.h \
+	../src/UndoHistory.h \
 	../src/UniConversion.h
 ChangeHistory.o: \
 	../src/ChangeHistory.cxx \
@@ -478,6 +480,18 @@ Style.o: \
 	../src/Geometry.h \
 	../src/Platform.h \
 	../src/Style.h
+UndoHistory.o: \
+	../src/UndoHistory.cxx \
+	../include/ScintillaTypes.h \
+	../src/Debugging.h \
+	../src/Position.h \
+	../src/SplitVector.h \
+	../src/Partitioning.h \
+	../src/RunStyles.h \
+	../src/SparseVector.h \
+	../src/ChangeHistory.h \
+	../src/CellBuffer.h \
+	../src/UndoHistory.h
 UniConversion.o: \
 	../src/UniConversion.cxx \
 	../src/UniConversion.h
diff --git a/scintilla/gtk/makefile b/scintilla/gtk/makefile
index ffac7c643..05b262a2e 100644
--- a/scintilla/gtk/makefile
+++ b/scintilla/gtk/makefile
@@ -149,6 +149,7 @@ SRC_OBJS = \
 	RunStyles.o \
 	Selection.o \
 	Style.o \
+	UndoHistory.o \
 	UniConversion.o \
 	UniqueString.o \
 	ViewStyle.o \
diff --git a/scintilla/include/Scintilla.h b/scintilla/include/Scintilla.h
index b100bf8a7..1dd69713e 100644
--- a/scintilla/include/Scintilla.h
+++ b/scintilla/include/Scintilla.h
@@ -339,6 +339,20 @@ typedef sptr_t (*SciFnDirectStatus)(sptr_t ptr, unsigned int iMessage, uptr_t wP
 #define SCI_GETCHARACTERCATEGORYOPTIMIZATION 2721
 #define SCI_BEGINUNDOACTION 2078
 #define SCI_ENDUNDOACTION 2079
+#define SCI_GETUNDOACTIONS 2790
+#define SCI_SETUNDOSAVEPOINT 2791
+#define SCI_GETUNDOSAVEPOINT 2792
+#define SCI_SETUNDODETACH 2793
+#define SCI_GETUNDODETACH 2794
+#define SCI_SETUNDOTENTATIVE 2795
+#define SCI_GETUNDOTENTATIVE 2796
+#define SCI_SETUNDOCURRENT 2797
+#define SCI_GETUNDOCURRENT 2798
+#define SCI_PUSHUNDOACTIONTYPE 2800
+#define SCI_CHANGELASTUNDOACTIONTEXT 2801
+#define SCI_GETUNDOACTIONTYPE 2802
+#define SCI_GETUNDOACTIONPOSITION 2803
+#define SCI_GETUNDOACTIONTEXT 2804
 #define INDIC_PLAIN 0
 #define INDIC_SQUIGGLE 1
 #define INDIC_TT 2
diff --git a/scintilla/include/Scintilla.iface b/scintilla/include/Scintilla.iface
index cfa51aefc..442f1772c 100644
--- a/scintilla/include/Scintilla.iface
+++ b/scintilla/include/Scintilla.iface
@@ -833,6 +833,48 @@ fun void BeginUndoAction=2078(,)
 # End a sequence of actions that is undone and redone as a unit.
 fun void EndUndoAction=2079(,)
 
+# How many undo actions are in the history?
+get int GetUndoActions=2790(,)
+
+# Set action as the save point
+set void SetUndoSavePoint=2791(int action,)
+
+# Which action is the save point?
+get int GetUndoSavePoint=2792(,)
+
+# Set action as the detach point
+set void SetUndoDetach=2793(int action,)
+
+# Which action is the detach point?
+get int GetUndoDetach=2794(,)
+
+# Set action as the tentative point
+set void SetUndoTentative=2795(int action,)
+
+# Which action is the tentative point?
+get int GetUndoTentative=2796(,)
+
+# Set action as the current point
+set void SetUndoCurrent=2797(int action,)
+
+# Which action is the current point?
+get int GetUndoCurrent=2798(,)
+
+# Push one action onto undo history with no text
+fun void PushUndoActionType=2800(int type, position pos)
+
+# Set the text and length of the most recently pushed action
+fun void ChangeLastUndoActionText=2801(position length, string text)
+
+# What is the type of an action?
+get int GetUndoActionType=2802(int action,)
+
+# What is the position of an action?
+get position GetUndoActionPosition=2803(int action,)
+
+# What is the text of an action?
+get int GetUndoActionText=2804(int action, stringresult text)
+
 # Indicator style enumeration and some constants
 enu IndicatorStyle=INDIC_
 val INDIC_PLAIN=0
diff --git a/scintilla/include/ScintillaCall.h b/scintilla/include/ScintillaCall.h
index 0ce4366d7..2f2e4f0cb 100644
--- a/scintilla/include/ScintillaCall.h
+++ b/scintilla/include/ScintillaCall.h
@@ -245,6 +245,21 @@ public:
 	int CharacterCategoryOptimization();
 	void BeginUndoAction();
 	void EndUndoAction();
+	int UndoActions();
+	void SetUndoSavePoint(int action);
+	int UndoSavePoint();
+	void SetUndoDetach(int action);
+	int UndoDetach();
+	void SetUndoTentative(int action);
+	int UndoTentative();
+	void SetUndoCurrent(int action);
+	int UndoCurrent();
+	void PushUndoActionType(int type, Position pos);
+	void ChangeLastUndoActionText(Position length, const char *text);
+	int UndoActionType(int action);
+	Position UndoActionPosition(int action);
+	int UndoActionText(int action, char *text);
+	std::string UndoActionText(int action);
 	void IndicSetStyle(int indicator, Scintilla::IndicatorStyle indicatorStyle);
 	Scintilla::IndicatorStyle IndicGetStyle(int indicator);
 	void IndicSetFore(int indicator, Colour fore);
diff --git a/scintilla/include/ScintillaMessages.h b/scintilla/include/ScintillaMessages.h
index 2befeb363..31a4435c4 100644
--- a/scintilla/include/ScintillaMessages.h
+++ b/scintilla/include/ScintillaMessages.h
@@ -171,6 +171,20 @@ enum class Message {
 	GetCharacterCategoryOptimization = 2721,
 	BeginUndoAction = 2078,
 	EndUndoAction = 2079,
+	GetUndoActions = 2790,
+	SetUndoSavePoint = 2791,
+	GetUndoSavePoint = 2792,
+	SetUndoDetach = 2793,
+	GetUndoDetach = 2794,
+	SetUndoTentative = 2795,
+	GetUndoTentative = 2796,
+	SetUndoCurrent = 2797,
+	GetUndoCurrent = 2798,
+	PushUndoActionType = 2800,
+	ChangeLastUndoActionText = 2801,
+	GetUndoActionType = 2802,
+	GetUndoActionPosition = 2803,
+	GetUndoActionText = 2804,
 	IndicSetStyle = 2080,
 	IndicGetStyle = 2081,
 	IndicSetFore = 2082,
diff --git a/scintilla/qt/ScintillaEdit/ScintillaDocument.cpp b/scintilla/qt/ScintillaEdit/ScintillaDocument.cpp
index 77882f822..2e29def38 100644
--- a/scintilla/qt/ScintillaEdit/ScintillaDocument.cpp
+++ b/scintilla/qt/ScintillaEdit/ScintillaDocument.cpp
@@ -89,7 +89,7 @@ void WatcherHelper::NotifyErrorOccurred(Document *, void *, Status status) {
 }
 
 ScintillaDocument::ScintillaDocument(QObject *parent, void *pdoc_) :
-    QObject(parent), pdoc(pdoc_), docWatcher(nullptr) {
+    QObject(parent), pdoc(static_cast<Scintilla::IDocumentEditable *>(pdoc_)), docWatcher(nullptr) {
     if (!pdoc) {
 	pdoc = new Document(DocumentOption::Default);
     }
@@ -153,8 +153,8 @@ bool ScintillaDocument::is_collecting_undo() {
     return (static_cast<Document *>(pdoc))->IsCollectingUndo();
 }
 
-void ScintillaDocument::begin_undo_action() {
-    (static_cast<Document *>(pdoc))->BeginUndoAction();
+void ScintillaDocument::begin_undo_action(bool coalesceWithPrior) {
+    (static_cast<Document *>(pdoc))->BeginUndoAction(coalesceWithPrior);
 }
 
 void ScintillaDocument::end_undo_action() {
diff --git a/scintilla/qt/ScintillaEdit/ScintillaDocument.h b/scintilla/qt/ScintillaEdit/ScintillaDocument.h
index 17e40295e..3bd369473 100644
--- a/scintilla/qt/ScintillaEdit/ScintillaDocument.h
+++ b/scintilla/qt/ScintillaEdit/ScintillaDocument.h
@@ -23,11 +23,16 @@ class WatcherHelper;
 #endif
 #endif
 
+// Forward declaration
+namespace Scintilla {
+    class IDocumentEditable;
+}
+
 class EXPORT_IMPORT_API ScintillaDocument : public QObject
 {
     Q_OBJECT
 
-    void *pdoc;
+    Scintilla::IDocumentEditable *pdoc;
     WatcherHelper *docWatcher;
 
 public:
@@ -45,7 +50,7 @@ public:
     void delete_undo_history();
     bool set_undo_collection(bool collect_undo);
     bool is_collecting_undo();
-    void begin_undo_action();
+    void begin_undo_action(bool coalesceWithPrior = false);
     void end_undo_action();
     void set_save_point();
     bool is_save_point();
diff --git a/scintilla/qt/ScintillaEdit/ScintillaEdit.pro b/scintilla/qt/ScintillaEdit/ScintillaEdit.pro
index 9b06cb210..105068363 100644
--- a/scintilla/qt/ScintillaEdit/ScintillaEdit.pro
+++ b/scintilla/qt/ScintillaEdit/ScintillaEdit.pro
@@ -13,7 +13,7 @@ TEMPLATE = lib
 CONFIG += lib_bundle
 CONFIG += c++1z
 
-VERSION = 5.4.1
+VERSION = 5.4.2
 
 SOURCES += \
     ScintillaEdit.cpp \
@@ -23,6 +23,7 @@ SOURCES += \
     ../ScintillaEditBase/ScintillaEditBase.cpp \
     ../../src/XPM.cxx \
     ../../src/ViewStyle.cxx \
+    ../../src/UndoHistory.cxx \
     ../../src/UniqueString.cxx \
     ../../src/UniConversion.cxx \
     ../../src/Style.cxx \
diff --git a/scintilla/qt/ScintillaEditBase/ScintillaEditBase.pro b/scintilla/qt/ScintillaEditBase/ScintillaEditBase.pro
index 33ac3f2e1..cabd4bf9c 100644
--- a/scintilla/qt/ScintillaEditBase/ScintillaEditBase.pro
+++ b/scintilla/qt/ScintillaEditBase/ScintillaEditBase.pro
@@ -13,7 +13,7 @@ TEMPLATE = lib
 CONFIG += lib_bundle
 CONFIG += c++1z
 
-VERSION = 5.4.1
+VERSION = 5.4.2
 
 SOURCES += \
     PlatQt.cpp \
@@ -23,6 +23,7 @@ SOURCES += \
     ../../src/ViewStyle.cxx \
     ../../src/UniqueString.cxx \
     ../../src/UniConversion.cxx \
+    ../../src/UndoHistory.cxx \
     ../../src/Style.cxx \
     ../../src/Selection.cxx \
     ../../src/ScintillaBase.cxx \
@@ -58,6 +59,7 @@ HEADERS  += \
     ScintillaEditBase.h \
     ../../src/XPM.h \
     ../../src/ViewStyle.h \
+    ../../src/UndoHistory.h \
     ../../src/UniConversion.h \
     ../../src/Style.h \
     ../../src/SplitVector.h \
diff --git a/scintilla/scripts/HeaderOrder.txt b/scintilla/scripts/HeaderOrder.txt
index c17d1897b..5b57a789c 100644
--- a/scintilla/scripts/HeaderOrder.txt
+++ b/scintilla/scripts/HeaderOrder.txt
@@ -122,6 +122,7 @@
 #include "ContractionState.h"
 #include "ChangeHistory.h"
 #include "CellBuffer.h"
+#include "UndoHistory.h"
 #include "PerLine.h"
 #include "CallTip.h"
 #include "KeyMap.h"
diff --git a/scintilla/src/CellBuffer.cxx b/scintilla/src/CellBuffer.cxx
index b0068bf62..4fcc2117d 100644
--- a/scintilla/src/CellBuffer.cxx
+++ b/scintilla/src/CellBuffer.cxx
@@ -32,6 +32,7 @@
 #include "SparseVector.h"
 #include "ChangeHistory.h"
 #include "CellBuffer.h"
+#include "UndoHistory.h"
 #include "UniConversion.h"
 
 namespace Scintilla::Internal {
@@ -329,292 +330,13 @@ public:
 	}
 };
 
-Action::Action() noexcept {
-	at = ActionType::start;
-	position = 0;
-	lenData = 0;
-	mayCoalesce = false;
-}
-
-void Action::Create(ActionType at_, Sci::Position position_, const char *data_, Sci::Position lenData_, bool mayCoalesce_) {
-	data = nullptr;
-	position = position_;
-	at = at_;
-	if (lenData_) {
-		data = std::make_unique<char[]>(lenData_);
-		memcpy(&data[0], data_, lenData_);
-	}
-	lenData = lenData_;
-	mayCoalesce = mayCoalesce_;
-}
-
-void Action::Clear() noexcept {
-	data = nullptr;
-	lenData = 0;
-}
-
-// The undo history stores a sequence of user operations that represent the user's view of the
-// commands executed on the text.
-// Each user operation contains a sequence of text insertion and text deletion actions.
-// All the user operations are stored in a list of individual actions with 'start' actions used
-// as delimiters between user operations.
-// Initially there is one start action in the history.
-// As each action is performed, it is recorded in the history. The action may either become
-// part of the current user operation or may start a new user operation. If it is to be part of the
-// current operation, then it overwrites the current last action. If it is to be part of a new
-// operation, it is appended after the current last action.
-// After writing the new action, a new start action is appended at the end of the history.
-// The decision of whether to start a new user operation is based upon two factors. If a
-// compound operation has been explicitly started by calling BeginUndoAction and no matching
-// EndUndoAction (these calls nest) has been called, then the action is coalesced into the current
-// operation. If there is no outstanding BeginUndoAction call then a new operation is started
-// unless it looks as if the new action is caused by the user typing or deleting a stream of text.
-// Sequences that look like typing or deletion are coalesced into a single user operation.
-
-UndoHistory::UndoHistory() {
-
-	actions.resize(3);
-	maxAction = 0;
-	currentAction = 0;
-	undoSequenceDepth = 0;
-	savePoint = 0;
-	tentativePoint = -1;
-
-	actions[currentAction].Create(ActionType::start);
-}
-
-void UndoHistory::EnsureUndoRoom() {
-	// Have to test that there is room for 2 more actions in the array
-	// as two actions may be created by the calling function
-	if (static_cast<size_t>(currentAction) >= (actions.size() - 2)) {
-		// Run out of undo nodes so extend the array
-		actions.resize(actions.size() * 2);
-	}
-}
-
-const char *UndoHistory::AppendAction(ActionType at, Sci::Position position, const char *data, Sci::Position lengthData,
-	bool &startSequence, bool mayCoalesce) {
-	EnsureUndoRoom();
-	//Platform::DebugPrintf("%% %d action %d %d %d\n", at, position, lengthData, currentAction);
-	//Platform::DebugPrintf("^ %d action %d %d\n", actions[currentAction - 1].at,
-	//	actions[currentAction - 1].position, actions[currentAction - 1].lenData);
-	if (currentAction < savePoint) {
-		savePoint = -1;
-		if (!detach) {
-			detach = currentAction;
-		}
-	} else if (detach && (*detach > currentAction)) {
-		detach = currentAction;
-	}
-	const int oldCurrentAction = currentAction;
-	if (currentAction >= 1) {
-		if (0 == undoSequenceDepth) {
-			// Top level actions may not always be coalesced
-			ptrdiff_t targetAct = -1;
-			const Action *actPrevious = &(actions[currentAction + targetAct]);
-			// Container actions may forward the coalesce state of Scintilla Actions.
-			while ((actPrevious->at == ActionType::container) && actPrevious->mayCoalesce) {
-				targetAct--;
-				actPrevious = &(actions[currentAction + targetAct]);
-			}
-			// See if current action can be coalesced into previous action
-			// Will work if both are inserts or deletes and position is same
-			if ((currentAction == savePoint) || (currentAction == tentativePoint)) {
-				currentAction++;
-			} else if (!actions[currentAction].mayCoalesce) {
-				// Not allowed to coalesce if this set
-				currentAction++;
-			} else if (!mayCoalesce || !actPrevious->mayCoalesce) {
-				currentAction++;
-			} else if (at == ActionType::container || actions[currentAction].at == ActionType::container) {
-				;	// A coalescible containerAction
-			} else if ((at != actPrevious->at) && (actPrevious->at != ActionType::start)) {
-				currentAction++;
-			} else if ((at == ActionType::insert) &&
-			           (position != (actPrevious->position + actPrevious->lenData))) {
-				// Insertions must be immediately after to coalesce
-				currentAction++;
-			} else if (at == ActionType::remove) {
-				if ((lengthData == 1) || (lengthData == 2)) {
-					if ((position + lengthData) == actPrevious->position) {
-						; // Backspace -> OK
-					} else if (position == actPrevious->position) {
-						; // Delete -> OK
-					} else {
-						// Removals must be at same position to coalesce
-						currentAction++;
-					}
-				} else {
-					// Removals must be of one character to coalesce
-					currentAction++;
-				}
-			} else {
-				// Action coalesced.
-			}
-
-		} else {
-			// Actions not at top level are always coalesced unless this is after return to top level
-			if (!actions[currentAction].mayCoalesce)
-				currentAction++;
-		}
-	} else {
-		currentAction++;
-	}
-	startSequence = oldCurrentAction != currentAction;
-	const int actionWithData = currentAction;
-	actions[currentAction].Create(at, position, data, lengthData, mayCoalesce);
-	currentAction++;
-	actions[currentAction].Create(ActionType::start);
-	maxAction = currentAction;
-	return actions[actionWithData].data.get();
-}
-
-void UndoHistory::BeginUndoAction() {
-	EnsureUndoRoom();
-	if (undoSequenceDepth == 0) {
-		if (actions[currentAction].at != ActionType::start) {
-			currentAction++;
-			actions[currentAction].Create(ActionType::start);
-			maxAction = currentAction;
-		}
-		actions[currentAction].mayCoalesce = false;
-	}
-	undoSequenceDepth++;
-}
-
-void UndoHistory::EndUndoAction() {
-	PLATFORM_ASSERT(undoSequenceDepth > 0);
-	EnsureUndoRoom();
-	undoSequenceDepth--;
-	if (0 == undoSequenceDepth) {
-		if (actions[currentAction].at != ActionType::start) {
-			currentAction++;
-			actions[currentAction].Create(ActionType::start);
-			maxAction = currentAction;
-		}
-		actions[currentAction].mayCoalesce = false;
-	}
-}
-
-void UndoHistory::DropUndoSequence() {
-	undoSequenceDepth = 0;
-}
-
-void UndoHistory::DeleteUndoHistory() {
-	for (int i = 1; i < maxAction; i++)
-		actions[i].Clear();
-	maxAction = 0;
-	currentAction = 0;
-	actions[currentAction].Create(ActionType::start);
-	savePoint = 0;
-	tentativePoint = -1;
-}
-
-void UndoHistory::SetSavePoint() noexcept {
-	savePoint = currentAction;
-	detach.reset();
-}
-
-bool UndoHistory::IsSavePoint() const noexcept {
-	return savePoint == currentAction;
-}
-
-bool UndoHistory::BeforeSavePoint() const noexcept {
-	return (savePoint < 0) || (savePoint > currentAction);
-}
-
-bool UndoHistory::BeforeReachableSavePoint() const noexcept {
-	return (savePoint >= 0) && !detach && (savePoint > currentAction);
-}
-
-bool UndoHistory::AfterSavePoint() const noexcept {
-	return (savePoint >= 0) && (savePoint <= currentAction);
-}
-
-bool UndoHistory::AfterDetachPoint() const noexcept {
-	return detach && (*detach < currentAction);
-}
-
-void UndoHistory::TentativeStart() {
-	tentativePoint = currentAction;
-}
-
-void UndoHistory::TentativeCommit() {
-	tentativePoint = -1;
-	// Truncate undo history
-	maxAction = currentAction;
-}
-
-bool UndoHistory::TentativeActive() const noexcept {
-	return tentativePoint >= 0;
-}
-
-int UndoHistory::TentativeSteps() noexcept {
-	// Drop any trailing startAction
-	if (actions[currentAction].at == ActionType::start && currentAction > 0)
-		currentAction--;
-	if (tentativePoint >= 0)
-		return currentAction - tentativePoint;
-	else
-		return -1;
-}
-
-bool UndoHistory::CanUndo() const noexcept {
-	return (currentAction > 0) && (maxAction > 0);
-}
-
-int UndoHistory::StartUndo() {
-	// Drop any trailing startAction
-	if (actions[currentAction].at == ActionType::start && currentAction > 0)
-		currentAction--;
-
-	// Count the steps in this action
-	int act = currentAction;
-	while (actions[act].at != ActionType::start && act > 0) {
-		act--;
-	}
-	return currentAction - act;
-}
-
-const Action &UndoHistory::GetUndoStep() const {
-	return actions[currentAction];
-}
-
-void UndoHistory::CompletedUndoStep() {
-	currentAction--;
-}
-
-bool UndoHistory::CanRedo() const noexcept {
-	return maxAction > currentAction;
-}
-
-int UndoHistory::StartRedo() {
-	// Drop any leading startAction
-	if (currentAction < maxAction && actions[currentAction].at == ActionType::start)
-		currentAction++;
-
-	// Count the steps in this action
-	int act = currentAction;
-	while (act < maxAction && actions[act].at != ActionType::start) {
-		act++;
-	}
-	return act - currentAction;
-}
-
-const Action &UndoHistory::GetRedoStep() const {
-	return actions[currentAction];
-}
-
-void UndoHistory::CompletedRedoStep() {
-	currentAction++;
-}
-
 CellBuffer::CellBuffer(bool hasStyles_, bool largeDocument_) :
 	hasStyles(hasStyles_), largeDocument(largeDocument_) {
 	readOnly = false;
 	utf8Substance = false;
 	utf8LineEnds = LineEndType::Default;
 	collectingUndo = true;
+	uh = std::make_unique<UndoHistory>();
 	if (largeDocument)
 		plv = std::make_unique<LineVector<Sci::Position>>();
 	else
@@ -704,12 +426,12 @@ const char *CellBuffer::InsertString(Sci::Position position, const char *s, Sci:
 		if (collectingUndo) {
 			// Save into the undo/redo stack, but only the characters - not the formatting
 			// This takes up about half load time
-			data = uh.AppendAction(ActionType::insert, position, s, insertLength, startSequence);
+			data = uh->AppendAction(ActionType::insert, position, s, insertLength, startSequence);
 		}
 
 		BasicInsertString(position, s, insertLength);
 		if (changeHistory) {
-			changeHistory->Insert(position, insertLength, collectingUndo, uh.BeforeReachableSavePoint());
+			changeHistory->Insert(position, insertLength, collectingUndo, uh->BeforeReachableSavePoint());
 		}
 	}
 	return data;
@@ -756,12 +478,12 @@ const char *CellBuffer::DeleteChars(Sci::Position position, Sci::Position delete
 			// Save into the undo/redo stack, but only the characters - not the formatting
 			// The gap would be moved to position anyway for the deletion so this doesn't cost extra
 			data = substance.RangePointer(position, deleteLength);
-			data = uh.AppendAction(ActionType::remove, position, data, deleteLength, startSequence);
+			data = uh->AppendAction(ActionType::remove, position, data, deleteLength, startSequence);
 		}
 
 		if (changeHistory) {
 			changeHistory->DeleteRangeSavingHistory(position, deleteLength,
-				uh.BeforeReachableSavePoint(), uh.AfterDetachPoint());
+				uh->BeforeReachableSavePoint(), uh->AfterOrAtDetachPoint());
 		}
 
 		BasicDeleteChars(position, deleteLength);
@@ -908,30 +630,30 @@ bool CellBuffer::HasStyles() const noexcept {
 }
 
 void CellBuffer::SetSavePoint() {
-	uh.SetSavePoint();
+	uh->SetSavePoint();
 	if (changeHistory) {
 		changeHistory->SetSavePoint();
 	}
 }
 
 bool CellBuffer::IsSavePoint() const noexcept {
-	return uh.IsSavePoint();
+	return uh->IsSavePoint();
 }
 
-void CellBuffer::TentativeStart() {
-	uh.TentativeStart();
+void CellBuffer::TentativeStart() noexcept {
+	uh->TentativeStart();
 }
 
-void CellBuffer::TentativeCommit() {
-	uh.TentativeCommit();
+void CellBuffer::TentativeCommit() noexcept {
+	uh->TentativeCommit();
 }
 
 int CellBuffer::TentativeSteps() noexcept {
-	return uh.TentativeSteps();
+	return uh->TentativeSteps();
 }
 
 bool CellBuffer::TentativeActive() const noexcept {
-	return uh.TentativeActive();
+	return uh->TentativeActive();
 }
 
 // Without undo
@@ -1330,9 +1052,9 @@ void CellBuffer::BasicDeleteChars(Sci::Position position, Sci::Position deleteLe
 	}
 }
 
-bool CellBuffer::SetUndoCollection(bool collectUndo) {
+bool CellBuffer::SetUndoCollection(bool collectUndo) noexcept {
 	collectingUndo = collectUndo;
-	uh.DropUndoSequence();
+	uh->DropUndoSequence();
 	return collectingUndo;
 }
 
@@ -1340,95 +1062,224 @@ bool CellBuffer::IsCollectingUndo() const noexcept {
 	return collectingUndo;
 }
 
-void CellBuffer::BeginUndoAction() {
-	uh.BeginUndoAction();
+void CellBuffer::BeginUndoAction(bool mayCoalesce) noexcept {
+	uh->BeginUndoAction(mayCoalesce);
 }
 
-void CellBuffer::EndUndoAction() {
-	uh.EndUndoAction();
+void CellBuffer::EndUndoAction() noexcept {
+	uh->EndUndoAction();
 }
 
 void CellBuffer::AddUndoAction(Sci::Position token, bool mayCoalesce) {
 	bool startSequence = false;
-	uh.AppendAction(ActionType::container, token, nullptr, 0, startSequence, mayCoalesce);
+	uh->AppendAction(ActionType::container, token, nullptr, 0, startSequence, mayCoalesce);
 }
 
-void CellBuffer::DeleteUndoHistory() {
-	uh.DeleteUndoHistory();
+void CellBuffer::DeleteUndoHistory() noexcept {
+	uh->DeleteUndoHistory();
 }
 
 bool CellBuffer::CanUndo() const noexcept {
-	return uh.CanUndo();
+	return uh->CanUndo();
 }
 
-int CellBuffer::StartUndo() {
-	return uh.StartUndo();
+int CellBuffer::StartUndo() noexcept {
+	return uh->StartUndo();
 }
 
-const Action &CellBuffer::GetUndoStep() const {
-	return uh.GetUndoStep();
+Action CellBuffer::GetUndoStep() const noexcept {
+	return uh->GetUndoStep();
 }
 
 void CellBuffer::PerformUndoStep() {
-	const Action &actionStep = uh.GetUndoStep();
-	if (changeHistory && uh.BeforeSavePoint()) {
+	const Action previousStep = uh->GetUndoStep();
+	// PreviousBeforeSavePoint and AfterDetachPoint are called since acting on the previous action,
+	// that is currentAction-1
+	if (changeHistory && uh->PreviousBeforeSavePoint()) {
 		changeHistory->StartReversion();
 	}
-	if (actionStep.at == ActionType::insert) {
-		if (substance.Length() < actionStep.lenData) {
+	if (previousStep.at == ActionType::insert) {
+		if (substance.Length() < previousStep.lenData) {
 			throw std::runtime_error(
 				"CellBuffer::PerformUndoStep: deletion must be less than document length.");
 		}
 		if (changeHistory) {
-			changeHistory->DeleteRange(actionStep.position, actionStep.lenData,
-				uh.BeforeSavePoint() && !uh.AfterDetachPoint());
+			changeHistory->DeleteRange(previousStep.position, previousStep.lenData,
+				uh->PreviousBeforeSavePoint() && !uh->AfterDetachPoint());
 		}
-		BasicDeleteChars(actionStep.position, actionStep.lenData);
-	} else if (actionStep.at == ActionType::remove) {
-		BasicInsertString(actionStep.position, actionStep.data.get(), actionStep.lenData);
+		BasicDeleteChars(previousStep.position, previousStep.lenData);
+	} else if (previousStep.at == ActionType::remove) {
+		BasicInsertString(previousStep.position, previousStep.data, previousStep.lenData);
 		if (changeHistory) {
-			changeHistory->UndoDeleteStep(actionStep.position, actionStep.lenData, uh.AfterDetachPoint());
+			changeHistory->UndoDeleteStep(previousStep.position, previousStep.lenData, uh->AfterDetachPoint());
 		}
 	}
-	uh.CompletedUndoStep();
+	uh->CompletedUndoStep();
 }
 
 bool CellBuffer::CanRedo() const noexcept {
-	return uh.CanRedo();
+	return uh->CanRedo();
 }
 
-int CellBuffer::StartRedo() {
-	return uh.StartRedo();
+int CellBuffer::StartRedo() noexcept {
+	return uh->StartRedo();
 }
 
-const Action &CellBuffer::GetRedoStep() const {
-	return uh.GetRedoStep();
+Action CellBuffer::GetRedoStep() const noexcept {
+	return uh->GetRedoStep();
 }
 
 void CellBuffer::PerformRedoStep() {
-	const Action &actionStep = uh.GetRedoStep();
+	const Action actionStep = uh->GetRedoStep();
 	if (actionStep.at == ActionType::insert) {
-		BasicInsertString(actionStep.position, actionStep.data.get(), actionStep.lenData);
+		BasicInsertString(actionStep.position, actionStep.data, actionStep.lenData);
 		if (changeHistory) {
 			changeHistory->Insert(actionStep.position, actionStep.lenData, collectingUndo,
-				uh.BeforeSavePoint() && !uh.AfterDetachPoint());
+				uh->BeforeSavePoint() && !uh->AfterOrAtDetachPoint());
 		}
 	} else if (actionStep.at == ActionType::remove) {
 		if (changeHistory) {
 			changeHistory->DeleteRangeSavingHistory(actionStep.position, actionStep.lenData,
-				uh.BeforeReachableSavePoint(), uh.AfterDetachPoint());
+				uh->BeforeReachableSavePoint(), uh->AfterOrAtDetachPoint());
 		}
 		BasicDeleteChars(actionStep.position, actionStep.lenData);
 	}
-	if (changeHistory && uh.AfterSavePoint()) {
+	if (changeHistory && uh->AfterSavePoint()) {
 		changeHistory->EndReversion();
 	}
-	uh.CompletedRedoStep();
+	uh->CompletedRedoStep();
+}
+
+int CellBuffer::UndoActions() const noexcept {
+	return uh->Actions();
+}
+
+void CellBuffer::SetUndoSavePoint(int action) noexcept {
+	uh->SetSavePoint(action);
+}
+
+int CellBuffer::UndoSavePoint() const noexcept {
+	return uh->SavePoint();
+}
+
+void CellBuffer::SetUndoDetach(int action) noexcept {
+	uh->SetDetachPoint(action);
+}
+
+int CellBuffer::UndoDetach() const noexcept {
+	return uh->DetachPoint();
+}
+
+void CellBuffer::SetUndoTentative(int action) noexcept {
+	uh->SetTentative(action);
+}
+
+int CellBuffer::UndoTentative() const noexcept {
+	return uh->TentativePoint();
+}
+
+namespace {
+
+void RestoreChangeHistory(const UndoHistory *uh, ChangeHistory *changeHistory) {
+	// Replay all undo actions into changeHistory
+	const int savePoint = uh->SavePoint();
+	const int detachPoint = uh->DetachPoint();
+	const int currentPoint = uh->Current();
+	for (int act = 0; act < uh->Actions(); act++) {
+		const ActionType type = static_cast<ActionType>(uh->Type(act) & ~coalesceFlag);
+		const Sci::Position position = uh->Position(act);
+		const Sci::Position length = uh->Length(act);
+		const bool beforeSave = act < savePoint || ((detachPoint >= 0) && (detachPoint > act));
+		const bool afterDetach = (detachPoint >= 0) && (detachPoint < act);
+		switch (type) {
+		case ActionType::insert:
+			changeHistory->Insert(position, length, true, beforeSave);
+			break;
+		case ActionType::remove:
+			changeHistory->DeleteRangeSavingHistory(position, length, beforeSave, afterDetach);
+			break;
+		default:
+			// Only insertions and deletions go into change history
+			break;
+		}
+		changeHistory->Check();
+	}
+	// Undo back to currentPoint, updating change history
+	for (int act = uh->Actions() - 1; act >= currentPoint; act--) {
+		const ActionType type = static_cast<ActionType>(uh->Type(act) & ~coalesceFlag);
+		const Sci::Position position = uh->Position(act);
+		const Sci::Position length = uh->Length(act);
+		const bool beforeSave = act < savePoint;
+		const bool afterDetach = (detachPoint >= 0) && (detachPoint < act);
+		if (beforeSave) {
+			changeHistory->StartReversion();
+		}
+		switch (type) {
+		case ActionType::insert:
+			changeHistory->DeleteRange(position, length, beforeSave && !afterDetach);
+			break;
+		case ActionType::remove:
+			changeHistory->UndoDeleteStep(position, length, afterDetach);
+			break;
+		default:
+			// Only insertions and deletions go into change history
+			break;
+		}
+		changeHistory->Check();
+	}
+}
+
+}
+
+void CellBuffer::SetUndoCurrent(int action) {
+	uh->SetCurrent(action, Length());
+	if (changeHistory) {
+		if ((uh->DetachPoint() >= 0) && (uh->SavePoint() >= 0)) {
+			// Can't have a valid save point and a valid detach point at same time
+			uh->DeleteUndoHistory();
+			changeHistory.reset();
+			throw std::runtime_error("UndoHistory::SetCurrent: invalid undo history.");
+		}
+		const intptr_t sizeChange = uh->Delta(action);
+		const intptr_t lengthOriginal = Length() - sizeChange;
+		// Recreate empty change history
+		changeHistory = std::make_unique<ChangeHistory>(lengthOriginal);
+		RestoreChangeHistory(uh.get(), changeHistory.get());
+		if (Length() != changeHistory->Length()) {
+			uh->DeleteUndoHistory();
+			changeHistory.reset();
+			throw std::runtime_error("UndoHistory::SetCurrent: invalid undo history.");
+		}
+	}
+}
+
+int CellBuffer::UndoCurrent() const noexcept {
+	return uh->Current();
+}
+
+int CellBuffer::UndoActionType(int action) const noexcept {
+	return uh->Type(action);
+}
+
+Sci::Position CellBuffer::UndoActionPosition(int action) const noexcept {
+	return uh->Position(action);
+}
+
+std::string_view CellBuffer::UndoActionText(int action) const noexcept {
+	return uh->Text(action);
+}
+
+void CellBuffer::PushUndoActionType(int type, Sci::Position position) {
+	uh->PushUndoActionType(type, position);
+}
+
+void CellBuffer::ChangeLastUndoActionText(size_t length, const char *text) {
+	uh->ChangeLastUndoActionText(length, text);
 }
 
 void CellBuffer::ChangeHistorySet(bool set) {
 	if (set) {
-		if (!changeHistory && !uh.CanUndo()) {
+		if (!changeHistory && !uh->CanUndo()) {
 			changeHistory = std::make_unique<ChangeHistory>(Length());
 		}
 	} else {
diff --git a/scintilla/src/CellBuffer.h b/scintilla/src/CellBuffer.h
index 68dd7285d..13ee6e9fe 100644
--- a/scintilla/src/CellBuffer.h
+++ b/scintilla/src/CellBuffer.h
@@ -20,79 +20,25 @@ public:
 	virtual void RemoveLine(Sci::Line line)=0;
 };
 
+class UndoHistory;
 class ChangeHistory;
+
 /**
  * The line vector contains information about each of the lines in a cell buffer.
  */
 class ILineVector;
 
-enum class ActionType { insert, remove, start, container };
+enum class ActionType : unsigned char { insert, remove, container };
 
 /**
- * Actions are used to store all the information required to perform one undo/redo step.
+ * Actions are used to return the information required to report one undo/redo step.
  */
-class Action {
-public:
-	ActionType at;
-	Sci::Position position;
-	std::unique_ptr<char[]> data;
-	Sci::Position lenData;
-	bool mayCoalesce;
-
-	Action() noexcept;
-	void Create(ActionType at_, Sci::Position position_=0, const char *data_=nullptr, Sci::Position lenData_=0, bool mayCoalesce_=true);
-	void Clear() noexcept;
-};
-
-/**
- *
- */
-class UndoHistory {
-	std::vector<Action> actions;
-	int maxAction;
-	int currentAction;
-	int undoSequenceDepth;
-	int savePoint;
-	int tentativePoint;
-	std::optional<int> detach;
-
-	void EnsureUndoRoom();
-
-public:
-	UndoHistory();
-
-	const char *AppendAction(ActionType at, Sci::Position position, const char *data, Sci::Position lengthData, bool &startSequence, bool mayCoalesce=true);
-
-	void BeginUndoAction();
-	void EndUndoAction();
-	void DropUndoSequence();
-	void DeleteUndoHistory();
-
-	/// The save point is a marker in the undo stack where the container has stated that
-	/// the buffer was saved. Undo and redo can move over the save point.
-	void SetSavePoint() noexcept;
-	bool IsSavePoint() const noexcept;
-	bool BeforeSavePoint() const noexcept;
-	bool BeforeReachableSavePoint() const noexcept;
-	bool AfterSavePoint() const noexcept;
-	bool AfterDetachPoint() const noexcept;
-
-	// Tentative actions are used for input composition so that it can be undone cleanly
-	void TentativeStart();
-	void TentativeCommit();
-	bool TentativeActive() const noexcept;
-	int TentativeSteps() noexcept;
-
-	/// To perform an undo, StartUndo is called to retrieve the number of steps, then UndoStep is
-	/// called that many times. Similarly for redo.
-	bool CanUndo() const noexcept;
-	int StartUndo();
-	const Action &GetUndoStep() const;
-	void CompletedUndoStep();
-	bool CanRedo() const noexcept;
-	int StartRedo();
-	const Action &GetRedoStep() const;
-	void CompletedRedoStep();
+struct Action {
+	ActionType at = ActionType::insert;
+	bool mayCoalesce = false;
+	Sci::Position position = 0;
+	const char *data = nullptr;
+	Sci::Position lenData = 0;
 };
 
 struct SplitView {
@@ -137,7 +83,7 @@ private:
 	Scintilla::LineEndType utf8LineEnds;
 
 	bool collectingUndo;
-	UndoHistory uh;
+	std::unique_ptr<UndoHistory> uh;
 
 	std::unique_ptr<ChangeHistory> changeHistory;
 
@@ -211,29 +157,44 @@ public:
 	void SetSavePoint();
 	bool IsSavePoint() const noexcept;
 
-	void TentativeStart();
-	void TentativeCommit();
+	void TentativeStart() noexcept;
+	void TentativeCommit() noexcept;
 	bool TentativeActive() const noexcept;
 	int TentativeSteps() noexcept;
 
-	bool SetUndoCollection(bool collectUndo);
+	bool SetUndoCollection(bool collectUndo) noexcept;
 	bool IsCollectingUndo() const noexcept;
-	void BeginUndoAction();
-	void EndUndoAction();
+	void BeginUndoAction(bool mayCoalesce=false) noexcept;
+	void EndUndoAction() noexcept;
 	void AddUndoAction(Sci::Position token, bool mayCoalesce);
-	void DeleteUndoHistory();
+	void DeleteUndoHistory() noexcept;
 
 	/// To perform an undo, StartUndo is called to retrieve the number of steps, then UndoStep is
 	/// called that many times. Similarly for redo.
 	bool CanUndo() const noexcept;
-	int StartUndo();
-	const Action &GetUndoStep() const;
+	int StartUndo() noexcept;
+	Action GetUndoStep() const noexcept;
 	void PerformUndoStep();
 	bool CanRedo() const noexcept;
-	int StartRedo();
-	const Action &GetRedoStep() const;
+	int StartRedo() noexcept;
+	Action GetRedoStep() const noexcept;
 	void PerformRedoStep();
 
+	int UndoActions() const noexcept;
+	void SetUndoSavePoint(int action) noexcept;
+	int UndoSavePoint() const noexcept;
+	void SetUndoDetach(int action) noexcept;
+	int UndoDetach() const noexcept;
+	void SetUndoTentative(int action) noexcept;
+	int UndoTentative() const noexcept;
+	void SetUndoCurrent(int action);
+	int UndoCurrent() const noexcept;
+	int UndoActionType(int action) const noexcept;
+	Sci::Position UndoActionPosition(int action) const noexcept;
+	std::string_view UndoActionText(int action) const noexcept;
+	void PushUndoActionType(int type, Sci::Position position);
+	void ChangeLastUndoActionText(size_t length, const char *text);
+
 	void ChangeHistorySet(bool set);
 	[[nodiscard]] int EditionAt(Sci::Position pos) const noexcept;
 	[[nodiscard]] Sci::Position EditionEndRun(Sci::Position pos) const noexcept;
diff --git a/scintilla/src/Document.cxx b/scintilla/src/Document.cxx
index 0c48c67bb..f53bfe421 100644
--- a/scintilla/src/Document.cxx
+++ b/scintilla/src/Document.cxx
@@ -303,7 +303,7 @@ void Document::TentativeUndo() {
 			//Platform::DebugPrintf("Steps=%d\n", steps);
 			for (int step = 0; step < steps; step++) {
 				const Sci::Line prevLinesTotal = LinesTotal();
-				const Action &action = cb.GetUndoStep();
+				const Action action = cb.GetUndoStep();
 				if (action.at == ActionType::remove) {
 					NotifyModified(DocModification(
 									ModificationFlags::BeforeInsert | ModificationFlags::Undo, action));
@@ -338,7 +338,7 @@ void Document::TentativeUndo() {
 						modFlags |= ModificationFlags::MultilineUndoRedo;
 				}
 				NotifyModified(DocModification(modFlags, action.position, action.lenData,
-											   linesAdded, action.data.get()));
+											   linesAdded, action.data));
 			}
 
 			const bool endSavePoint = cb.IsSavePoint();
@@ -351,6 +351,62 @@ void Document::TentativeUndo() {
 	}
 }
 
+int Document::UndoActions() const noexcept {
+	return cb.UndoActions();
+}
+
+void Document::SetUndoSavePoint(int action) noexcept {
+	cb.SetUndoSavePoint(action);
+}
+
+int Document::UndoSavePoint() const noexcept {
+	return cb.UndoSavePoint();
+}
+
+void Document::SetUndoDetach(int action) noexcept {
+	cb.SetUndoDetach(action);
+}
+
+int Document::UndoDetach() const noexcept {
+	return cb.UndoDetach();
+}
+
+void Document::SetUndoTentative(int action) noexcept {
+	cb.SetUndoTentative(action);
+}
+
+int Document::UndoTentative() const noexcept {
+	return cb.UndoTentative();
+}
+
+void Document::SetUndoCurrent(int action) {
+	cb.SetUndoCurrent(action);
+}
+
+int Document::UndoCurrent() const noexcept {
+	return cb.UndoCurrent();
+}
+
+int Document::UndoActionType(int action) const noexcept {
+	return cb.UndoActionType(action);
+}
+
+Sci::Position Document::UndoActionPosition(int action) const noexcept {
+	return cb.UndoActionPosition(action);
+}
+
+std::string_view Document::UndoActionText(int action) const noexcept {
+	return cb.UndoActionText(action);
+}
+
+void Document::PushUndoActionType(int type, Sci::Position position) {
+	cb.PushUndoActionType(type, position);
+}
+
+void Document::ChangeLastUndoActionText(size_t length, const char *text) {
+	cb.ChangeLastUndoActionText(length, text);
+}
+
 int Document::GetMark(Sci::Line line, bool includeChangeHistory) const {
 	int marksHistory = 0;
 	if (includeChangeHistory && (line < LinesTotal())) {
@@ -1363,13 +1419,10 @@ Sci::Position Document::Undo() {
 			bool multiLine = false;
 			const int steps = cb.StartUndo();
 			//Platform::DebugPrintf("Steps=%d\n", steps);
-			Sci::Position coalescedRemovePos = -1;
-			Sci::Position coalescedRemoveLen = 0;
-			Sci::Position prevRemoveActionPos = -1;
-			Sci::Position prevRemoveActionLen = 0;
+			Range coalescedRemove;	// Default is empty at 0
 			for (int step = 0; step < steps; step++) {
 				const Sci::Line prevLinesTotal = LinesTotal();
-				const Action &action = cb.GetUndoStep();
+				const Action action = cb.GetUndoStep();
 				if (action.at == ActionType::remove) {
 					NotifyModified(DocModification(
 									ModificationFlags::BeforeInsert | ModificationFlags::Undo, action));
@@ -1377,12 +1430,6 @@ Sci::Position Document::Undo() {
 					DocModification dm(ModificationFlags::Container | ModificationFlags::Undo);
 					dm.token = action.position;
 					NotifyModified(dm);
-					if (!action.mayCoalesce) {
-						coalescedRemovePos = -1;
-						coalescedRemoveLen = 0;
-						prevRemoveActionPos = -1;
-						prevRemoveActionLen = 0;
-					}
 				} else {
 					NotifyModified(DocModification(
 									ModificationFlags::BeforeDelete | ModificationFlags::Undo, action));
@@ -1398,22 +1445,15 @@ Sci::Position Document::Undo() {
 				if (action.at == ActionType::remove) {
 					newPos += action.lenData;
 					modFlags |= ModificationFlags::InsertText;
-					if ((coalescedRemoveLen > 0) &&
-						(action.position == prevRemoveActionPos || action.position == (prevRemoveActionPos + prevRemoveActionLen))) {
-						coalescedRemoveLen += action.lenData;
-						newPos = coalescedRemovePos + coalescedRemoveLen;
+					if (coalescedRemove.Contains(action.position)) {
+						coalescedRemove.end += action.lenData;
+						newPos = coalescedRemove.end;
 					} else {
-						coalescedRemovePos = action.position;
-						coalescedRemoveLen = action.lenData;
+						coalescedRemove = Range(action.position, action.position + action.lenData);
 					}
-					prevRemoveActionPos = action.position;
-					prevRemoveActionLen = action.lenData;
 				} else if (action.at == ActionType::insert) {
 					modFlags |= ModificationFlags::DeleteText;
-					coalescedRemovePos = -1;
-					coalescedRemoveLen = 0;
-					prevRemoveActionPos = -1;
-					prevRemoveActionLen = 0;
+					coalescedRemove = Range(); 
 				}
 				if (steps > 1)
 					modFlags |= ModificationFlags::MultiStepUndoRedo;
@@ -1426,7 +1466,7 @@ Sci::Position Document::Undo() {
 						modFlags |= ModificationFlags::MultilineUndoRedo;
 				}
 				NotifyModified(DocModification(modFlags, action.position, action.lenData,
-											   linesAdded, action.data.get()));
+											   linesAdded, action.data));
 			}
 
 			const bool endSavePoint = cb.IsSavePoint();
@@ -1449,7 +1489,7 @@ Sci::Position Document::Redo() {
 			const int steps = cb.StartRedo();
 			for (int step = 0; step < steps; step++) {
 				const Sci::Line prevLinesTotal = LinesTotal();
-				const Action &action = cb.GetRedoStep();
+				const Action action = cb.GetRedoStep();
 				if (action.at == ActionType::insert) {
 					NotifyModified(DocModification(
 									ModificationFlags::BeforeInsert | ModificationFlags::Redo, action));
@@ -1486,7 +1526,7 @@ Sci::Position Document::Redo() {
 				}
 				NotifyModified(
 					DocModification(modFlags, action.position, action.lenData,
-									linesAdded, action.data.get()));
+									linesAdded, action.data));
 			}
 
 			const bool endSavePoint = cb.IsSavePoint();
@@ -2195,7 +2235,7 @@ Sci::Position Document::FindText(Sci::Position minPos, Sci::Position maxPos, con
 						for (int b = 1; b < widthCharBytes; b++) {
 							bytes[b] = cbView.CharAt(posIndexDocument + b);
 						}
-						widthChar = UTF8Classify(reinterpret_cast<const unsigned char *>(bytes), widthCharBytes) & UTF8MaskWidth;
+						widthChar = UTF8Classify(bytes, widthCharBytes) & UTF8MaskWidth;
 						if (!indexSearch) {	// First character
 							widthFirstCharacter = widthChar;
 						}
diff --git a/scintilla/src/Document.h b/scintilla/src/Document.h
index 5656975b1..a42bfc301 100644
--- a/scintilla/src/Document.h
+++ b/scintilla/src/Document.h
@@ -390,22 +390,37 @@ public:
 	Sci::Position Redo();
 	bool CanUndo() const noexcept { return cb.CanUndo(); }
 	bool CanRedo() const noexcept { return cb.CanRedo(); }
-	void DeleteUndoHistory() { cb.DeleteUndoHistory(); }
-	bool SetUndoCollection(bool collectUndo) {
+	void DeleteUndoHistory() noexcept { cb.DeleteUndoHistory(); }
+	bool SetUndoCollection(bool collectUndo) noexcept {
 		return cb.SetUndoCollection(collectUndo);
 	}
 	bool IsCollectingUndo() const noexcept { return cb.IsCollectingUndo(); }
-	void BeginUndoAction() { cb.BeginUndoAction(); }
-	void EndUndoAction() { cb.EndUndoAction(); }
+	void BeginUndoAction(bool coalesceWithPrior=false) noexcept { cb.BeginUndoAction(coalesceWithPrior); }
+	void EndUndoAction() noexcept { cb.EndUndoAction(); }
 	void AddUndoAction(Sci::Position token, bool mayCoalesce) { cb.AddUndoAction(token, mayCoalesce); }
 	void SetSavePoint();
 	bool IsSavePoint() const noexcept { return cb.IsSavePoint(); }
 
-	void TentativeStart() { cb.TentativeStart(); }
-	void TentativeCommit() { cb.TentativeCommit(); }
+	void TentativeStart() noexcept { cb.TentativeStart(); }
+	void TentativeCommit() noexcept { cb.TentativeCommit(); }
 	void TentativeUndo();
 	bool TentativeActive() const noexcept { return cb.TentativeActive(); }
 
+	int UndoActions() const noexcept;
+	void SetUndoSavePoint(int action) noexcept;
+	int UndoSavePoint() const noexcept;
+	void SetUndoDetach(int action) noexcept;
+	int UndoDetach() const noexcept;
+	void SetUndoTentative(int action) noexcept;
+	int UndoTentative() const noexcept;
+	void SetUndoCurrent(int action);
+	int UndoCurrent() const noexcept;
+	int UndoActionType(int action) const noexcept;
+	Sci::Position UndoActionPosition(int action) const noexcept;
+	std::string_view UndoActionText(int action) const noexcept;
+	void PushUndoActionType(int type, Sci::Position position);
+	void ChangeLastUndoActionText(size_t length, const char *text);
+
 	void ChangeHistorySet(bool set) { cb.ChangeHistorySet(set); }
 	[[nodiscard]] int EditionAt(Sci::Position pos) const noexcept { return cb.EditionAt(pos); }
 	[[nodiscard]] Sci::Position EditionEndRun(Sci::Position pos) const noexcept { return cb.EditionEndRun(pos); }
@@ -427,7 +442,7 @@ public:
 	static std::string TransformLineEnds(const char *s, size_t len, Scintilla::EndOfLine eolModeWanted);
 	void ConvertLineEnds(Scintilla::EndOfLine eolModeSet);
 	std::string_view EOLString() const noexcept;
-	void SetReadOnly(bool set) { cb.SetReadOnly(set); }
+	void SetReadOnly(bool set) noexcept { cb.SetReadOnly(set); }
 	bool IsReadOnly() const noexcept { return cb.IsReadOnly(); }
 	bool IsLarge() const noexcept { return cb.IsLarge(); }
 	Scintilla::DocumentOption Options() const noexcept;
@@ -565,7 +580,7 @@ class UndoGroup {
 	Document *pdoc;
 	bool groupNeeded;
 public:
-	UndoGroup(Document *pdoc_, bool groupNeeded_=true) :
+	UndoGroup(Document *pdoc_, bool groupNeeded_=true) noexcept :
 		pdoc(pdoc_), groupNeeded(groupNeeded_) {
 		if (groupNeeded) {
 			pdoc->BeginUndoAction();
@@ -626,7 +641,7 @@ public:
 		position(act.position),
 		length(act.lenData),
 		linesAdded(linesAdded_),
-		text(act.data.get()),
+		text(act.data),
 		line(0),
 		foldLevelNow(Scintilla::FoldLevel::None),
 		foldLevelPrev(Scintilla::FoldLevel::None),
diff --git a/scintilla/src/Editor.cxx b/scintilla/src/Editor.cxx
index 6058ccc6e..06d46ef6a 100644
--- a/scintilla/src/Editor.cxx
+++ b/scintilla/src/Editor.cxx
@@ -6128,6 +6128,15 @@ sptr_t Editor::BytesResult(sptr_t lParam, const unsigned char *val, size_t len)
 	return val ? len : 0;
 }
 
+sptr_t Editor::BytesResult(Scintilla::sptr_t lParam, std::string_view sv) noexcept {
+	// No NUL termination: sv.length() is number of valid/displayed bytes
+	if (lParam && !sv.empty()) {
+		char *ptr = CharPtrFromSPtr(lParam);
+		memcpy(ptr, sv.data(), sv.length());
+	}
+	return sv.length();
+}
+
 sptr_t Editor::WndProc(Message iMessage, uptr_t wParam, sptr_t lParam) {
 	//Platform::DebugPrintf("S start wnd proc %d %d %d\n",iMessage, wParam, lParam);
 
@@ -6374,8 +6383,8 @@ sptr_t Editor::WndProc(Message iMessage, uptr_t wParam, sptr_t lParam) {
 		break;
 
 	case Message::GetTargetText: {
-			std::string text = RangeText(targetRange.start.Position(), targetRange.end.Position());
-			return BytesResult(lParam, reinterpret_cast<const unsigned char *>(text.c_str()), text.length());
+			const std::string text = RangeText(targetRange.start.Position(), targetRange.end.Position());
+			return BytesResult(lParam, text);
 		}
 
 	case Message::ReplaceTarget:
@@ -6586,6 +6595,56 @@ sptr_t Editor::WndProc(Message iMessage, uptr_t wParam, sptr_t lParam) {
 		pdoc->EndUndoAction();
 		return 0;
 
+	case Message::GetUndoActions:
+		return pdoc->UndoActions();
+
+	case Message::SetUndoSavePoint:
+		pdoc->SetUndoSavePoint(static_cast<int>(wParam));
+		break;
+
+	case Message::GetUndoSavePoint:
+		return pdoc->UndoSavePoint();
+
+	case Message::SetUndoDetach:
+		pdoc->SetUndoDetach(static_cast<int>(wParam));
+		break;
+
+	case Message::GetUndoDetach:
+		return pdoc->UndoDetach();
+
+	case Message::SetUndoTentative:
+		pdoc->SetUndoTentative(static_cast<int>(wParam));
+		break;
+
+	case Message::GetUndoTentative:
+		return pdoc->UndoTentative();
+
+	case Message::SetUndoCurrent:
+		pdoc->SetUndoCurrent(static_cast<int>(wParam));
+		break;
+
+	case Message::GetUndoCurrent:
+		return pdoc->UndoCurrent();
+
+	case Message::GetUndoActionType:
+		return pdoc->UndoActionType(static_cast<int>(wParam));
+
+	case Message::GetUndoActionPosition:
+		return pdoc->UndoActionPosition(static_cast<int>(wParam));
+
+	case Message::GetUndoActionText: {
+		const std::string_view text = pdoc->UndoActionText(static_cast<int>(wParam));
+		return BytesResult(lParam, text);
+	}
+
+	case Message::PushUndoActionType:
+		pdoc->PushUndoActionType(static_cast<int>(wParam), lParam);
+		break;
+
+	case Message::ChangeLastUndoActionText:
+		pdoc->ChangeLastUndoActionText(wParam, CharPtrFromSPtr(lParam));
+		break;
+
 	case Message::GetCaretPeriod:
 		return caret.period;
 
diff --git a/scintilla/src/Editor.h b/scintilla/src/Editor.h
index 3145a25da..e5ce0792f 100644
--- a/scintilla/src/Editor.h
+++ b/scintilla/src/Editor.h
@@ -668,6 +668,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 
 	static Scintilla::sptr_t StringResult(Scintilla::sptr_t lParam, const char *val) noexcept;
 	static Scintilla::sptr_t BytesResult(Scintilla::sptr_t lParam, const unsigned char *val, size_t len) noexcept;
+	static Scintilla::sptr_t BytesResult(Scintilla::sptr_t lParam, std::string_view sv) noexcept;
 
 	// Set a variable controlling appearance to a value and invalidates the display
 	// if a change was made. Avoids extra text and the possibility of mistyping.
diff --git a/scintilla/src/RESearch.cxx b/scintilla/src/RESearch.cxx
index 217ba14ac..f4974c59b 100644
--- a/scintilla/src/RESearch.cxx
+++ b/scintilla/src/RESearch.cxx
@@ -502,7 +502,7 @@ const char *RESearch::Compile(const char *pattern, Sci::Position length, bool ca
 								} else {
 									i++;
 									p++;
-									int incr;
+									int incr = 0;
 									c2 = GetBackslashExpression(p, incr);
 									i += incr;
 									p += incr;
@@ -537,7 +537,7 @@ const char *RESearch::Compile(const char *pattern, Sci::Position length, bool ca
 				} else if (*p == '\\' && p[1]) {
 					i++;
 					p++;
-					int incr;
+					int incr = 0;
 					const int c = GetBackslashExpression(p, incr);
 					i += incr;
 					p += incr;
@@ -653,8 +653,8 @@ const char *RESearch::Compile(const char *pattern, Sci::Position length, bool ca
 						return badpat("Unmatched \\)");
 					}
 				} else {
-					int incr;
-					int c = GetBackslashExpression(p, incr);
+					int incr = 0;
+					const int c = GetBackslashExpression(p, incr);
 					i += incr;
 					p += incr;
 					if (c >= 0) {
@@ -938,8 +938,8 @@ Sci::Position RESearch::PMatch(const CharacterIndexer &ci, Sci::Position lp, Sci
 			Sci::Position llp = lp;		/* lazy lp for LCLO       */
 			Sci::Position e = NOTFOUND; /* extra pointer for CLO  */
 			while (llp >= are) {
-				Sci::Position q;
-				if ((q = PMatch(ci, llp, endp, ap)) != NOTFOUND) {
+				const Sci::Position q = PMatch(ci, llp, endp, ap);
+				if (q != NOTFOUND) {
 					e = q;
 					lp = llp;
 					if (op != LCLO) return e;
diff --git a/scintilla/src/Selection.cxx b/scintilla/src/Selection.cxx
index 3f9cdc440..3865622f4 100644
--- a/scintilla/src/Selection.cxx
+++ b/scintilla/src/Selection.cxx
@@ -218,19 +218,16 @@ SelectionRange &Selection::Rectangular() noexcept {
 }
 
 SelectionSegment Selection::Limits() const noexcept {
-	if (ranges.empty()) {
-		return SelectionSegment();
-	} else {
-		SelectionSegment sr(ranges[0].anchor, ranges[0].caret);
-		for (size_t i=1; i<ranges.size(); i++) {
-			sr.Extend(ranges[i].anchor);
-			sr.Extend(ranges[i].caret);
-		}
-		return sr;
+	PLATFORM_ASSERT(!ranges.empty());
+	SelectionSegment sr(ranges[0].anchor, ranges[0].caret);
+	for (size_t i=1; i<ranges.size(); i++) {
+		sr.Extend(ranges[i].anchor);
+		sr.Extend(ranges[i].caret);
 	}
+	return sr;
 }
 
-SelectionSegment Selection::LimitsForRectangularElseMain() const {
+SelectionSegment Selection::LimitsForRectangularElseMain() const noexcept {
 	if (IsRectangular()) {
 		return Limits();
 	} else {
@@ -343,10 +340,12 @@ void Selection::TrimOtherSelections(size_t r, SelectionRange range) noexcept {
 	}
 }
 
-void Selection::SetSelection(SelectionRange range) {
-	ranges.clear();
-	ranges.push_back(range);
-	mainRange = ranges.size() - 1;
+void Selection::SetSelection(SelectionRange range) noexcept {
+	if (ranges.size() > 1) {
+		ranges.erase(ranges.begin() + 1, ranges.end());
+	}
+	ranges[0] = range;
+	mainRange = 0;
 }
 
 void Selection::AddSelection(SelectionRange range) {
@@ -360,7 +359,7 @@ void Selection::AddSelectionWithoutTrim(SelectionRange range) {
 	mainRange = ranges.size() - 1;
 }
 
-void Selection::DropSelection(size_t r) {
+void Selection::DropSelection(size_t r) noexcept {
 	if ((ranges.size() > 1) && (r < ranges.size())) {
 		size_t mainNew = mainRange;
 		if (mainNew >= r) {
@@ -375,7 +374,7 @@ void Selection::DropSelection(size_t r) {
 	}
 }
 
-void Selection::DropAdditionalRanges() {
+void Selection::DropAdditionalRanges() noexcept {
 	SetSelection(RangeMain());
 }
 
@@ -425,17 +424,18 @@ Sci::Position Selection::VirtualSpaceFor(Sci::Position pos) const noexcept {
 	return virtualSpace;
 }
 
-void Selection::Clear() {
-	ranges.clear();
-	ranges.emplace_back();
-	mainRange = ranges.size() - 1;
+void Selection::Clear() noexcept {
+	if (ranges.size() > 1) {
+		ranges.erase(ranges.begin() + 1, ranges.end());
+	}
+	mainRange = 0;
 	selType = SelTypes::stream;
 	moveExtends = false;
 	ranges[mainRange].Reset();
 	rangeRectangular.Reset();
 }
 
-void Selection::RemoveDuplicates() {
+void Selection::RemoveDuplicates() noexcept {
 	for (size_t i=0; i<ranges.size()-1; i++) {
 		if (ranges[i].Empty()) {
 			size_t j=i+1;
diff --git a/scintilla/src/Selection.h b/scintilla/src/Selection.h
index 4d1a741e2..9d54f2193 100644
--- a/scintilla/src/Selection.h
+++ b/scintilla/src/Selection.h
@@ -166,7 +166,7 @@ public:
 	// This is for when you want to move the caret in response to a
 	// user direction command - for rectangular selections, use the range
 	// that covers all selected text otherwise return the main selection.
-	SelectionSegment LimitsForRectangularElseMain() const;
+	SelectionSegment LimitsForRectangularElseMain() const noexcept;
 	size_t Count() const noexcept;
 	size_t Main() const noexcept;
 	void SetMain(size_t r) noexcept;
@@ -183,19 +183,19 @@ public:
 	void MovePositions(bool insertion, Sci::Position startChange, Sci::Position length) noexcept;
 	void TrimSelection(SelectionRange range) noexcept;
 	void TrimOtherSelections(size_t r, SelectionRange range) noexcept;
-	void SetSelection(SelectionRange range);
+	void SetSelection(SelectionRange range) noexcept;
 	void AddSelection(SelectionRange range);
 	void AddSelectionWithoutTrim(SelectionRange range);
-	void DropSelection(size_t r);
-	void DropAdditionalRanges();
+	void DropSelection(size_t r) noexcept;
+	void DropAdditionalRanges() noexcept;
 	void TentativeSelection(SelectionRange range);
 	void CommitTentative() noexcept;
 	InSelection RangeType(size_t r) const noexcept;
 	InSelection CharacterInSelection(Sci::Position posCharacter) const noexcept;
 	InSelection InSelectionForEOL(Sci::Position pos) const noexcept;
 	Sci::Position VirtualSpaceFor(Sci::Position pos) const noexcept;
-	void Clear();
-	void RemoveDuplicates();
+	void Clear() noexcept;
+	void RemoveDuplicates() noexcept;
 	void RotateMain() noexcept;
 	bool Tentative() const noexcept { return tentativeMain; }
 	std::vector<SelectionRange> RangesCopy() const {
diff --git a/scintilla/src/UndoHistory.cxx b/scintilla/src/UndoHistory.cxx
new file mode 100644
index 000000000..c94d0690c
--- /dev/null
+++ b/scintilla/src/UndoHistory.cxx
@@ -0,0 +1,622 @@
+// Scintilla source code edit control
+/** @file UndoHistory.cxx
+ ** Manages undo for the document.
+ **/
+// Copyright 1998-2024 by Neil Hodgson <neilh@scintilla.org>
+// The License.txt file describes the conditions under which this software may be distributed.
+
+#include <cstddef>
+#include <cstdlib>
+#include <cstdint>
+#include <cassert>
+#include <cstring>
+#include <cstdio>
+#include <cstdarg>
+#include <climits>
+
+#include <stdexcept>
+#include <string>
+#include <string_view>
+#include <vector>
+#include <optional>
+#include <algorithm>
+#include <memory>
+
+#include "ScintillaTypes.h"
+
+#include "Debugging.h"
+
+#include "Position.h"
+#include "SplitVector.h"
+#include "Partitioning.h"
+#include "RunStyles.h"
+#include "SparseVector.h"
+#include "ChangeHistory.h"
+#include "CellBuffer.h"
+#include "UndoHistory.h"
+
+namespace Scintilla::Internal {
+
+template <typename T>
+void VectorTruncate(std::vector<T> &v, size_t length) noexcept {
+	v.erase(v.begin() + length, v.end());
+}
+
+constexpr size_t byteMask = UINT8_MAX;
+constexpr size_t byteBits = 8;
+constexpr size_t maxElementSize = 8;
+
+size_t ReadValue(const uint8_t *bytes, size_t length) noexcept {
+	size_t value = 0;
+	for (size_t i = 0; i < length; i++) {
+		value = (value << byteBits) + bytes[i];
+	}
+	return value;
+}
+
+void WriteValue(uint8_t *bytes, size_t length, size_t value) noexcept {
+	for (size_t i = 0; i < length; i++) {
+		bytes[length - i - 1] = value & byteMask;
+		value = value >> byteBits;
+	}
+}
+
+size_t ScaledVector::Size() const noexcept {
+	return bytes.size() / element.size;
+}
+
+size_t ScaledVector::ValueAt(size_t index) const noexcept {
+	return ReadValue(bytes.data() + index * element.size, element.size);
+}
+
+intptr_t ScaledVector::SignedValueAt(size_t index) const noexcept {
+	return ReadValue(bytes.data() + index * element.size, element.size);
+}
+
+constexpr SizeMax ElementForValue(size_t value) noexcept {
+	size_t maxN = byteMask;
+	for (size_t i = 1; i < maxElementSize; i++) {
+		if (value <= maxN) {
+			return { i, maxN };
+		}
+		maxN = (maxN << byteBits) + byteMask;
+	}
+	return { 1, byteMask };
+}
+
+void ScaledVector::SetValueAt(size_t index, size_t value) {
+	// Check if value fits, if not then expand
+	if (value > element.maxValue) {
+		const SizeMax elementForValue = ElementForValue(value);
+		const size_t length = bytes.size() / element.size;
+		std::vector<uint8_t> bytesNew(elementForValue.size * length);
+		for (size_t i = 0; i < length; i++) {
+			const uint8_t *source = bytes.data() + i * element.size;
+			uint8_t *destination = bytesNew.data() + (i+1) * elementForValue.size - element.size;
+			memcpy(destination, source, element.size);
+		}
+		std::swap(bytes, bytesNew);
+		element = elementForValue;
+	}
+	WriteValue(bytes.data() + index * element.size, element.size, value);
+}
+
+void ScaledVector::ClearValueAt(size_t index) noexcept {
+	// 0 fits in any size element so no expansion needed so no exceptions 
+	WriteValue(bytes.data() + index * element.size, element.size, 0);
+}
+
+void ScaledVector::Clear() noexcept {
+	bytes.clear();
+}
+
+void ScaledVector::Truncate(size_t length) noexcept {
+	VectorTruncate(bytes, length * element.size);
+	assert(bytes.size() == length * element.size);
+}
+
+void ScaledVector::ReSize(size_t length) {
+	bytes.resize(length * element.size);
+}
+
+void ScaledVector::PushBack() {
+	ReSize(Size() + 1);
+}
+
+size_t ScaledVector::SizeInBytes() const noexcept {
+	return bytes.size();
+}
+
+UndoActionType::UndoActionType() noexcept : at(ActionType::insert), mayCoalesce(false) {
+}
+
+UndoActions::UndoActions() noexcept = default;
+
+void UndoActions::Truncate(size_t length) noexcept {
+	VectorTruncate(types, length);
+	assert(types.size() == length);
+	positions.Truncate(length);
+	lengths.Truncate(length);
+}
+
+void UndoActions::PushBack() {
+	types.emplace_back();
+	positions.PushBack();
+	lengths.PushBack();
+}
+
+void UndoActions::Clear() noexcept {
+	types.clear();
+	positions.Clear();
+	lengths.Clear();
+}
+
+intptr_t UndoActions::SSize() const noexcept {
+	return types.size();
+}
+
+void UndoActions::Create(size_t index, ActionType at_, Sci::Position position_, Sci::Position lenData_, bool mayCoalesce_) {
+	types[index].at = at_;
+	types[index].mayCoalesce = mayCoalesce_;
+	positions.SetValueAt(index, position_);
+	lengths.SetValueAt(index, lenData_);
+}
+
+bool UndoActions::AtStart(size_t index) const noexcept {
+	if (index == 0) {
+		return true;
+	}
+	return !types[index-1].mayCoalesce;
+}
+
+size_t UndoActions::LengthTo(size_t index) const noexcept {
+	size_t sum = 0;
+	for (size_t act = 0; act < index; act++) {
+		sum += lengths.ValueAt(act);
+	}
+	return sum;
+}
+
+void ScrapStack::Clear() noexcept {
+	stack.clear();
+	current = 0;
+}
+
+const char *ScrapStack::Push(const char *text, size_t length) {
+	if (current < stack.length()) {
+		stack.resize(current);
+	}
+	stack.append(text, length);
+	current = stack.length();
+	return stack.data() + current - length;
+}
+
+void ScrapStack::SetCurrent(size_t position) noexcept {
+	current = position;
+}
+
+void ScrapStack::MoveForward(size_t length) noexcept {
+	if ((current + length) <= stack.length()) {
+		current += length;
+	}
+}
+
+void ScrapStack::MoveBack(size_t length) noexcept {
+	if (current >= length) {
+		current -= length;
+	}
+}
+
+const char *ScrapStack::CurrentText() const noexcept {
+	return stack.data() + current;
+}
+
+const char *ScrapStack::TextAt(size_t position) const noexcept {
+	return stack.data() + position;
+}
+
+// The undo history stores a sequence of user operations that represent the user's view of the
+// commands executed on the text.
+// Each user operation contains a sequence of text insertion and text deletion actions.
+// All the user operations are stored in a list of individual actions.
+// A false 'mayCoalesce' flag acts as an end to a user operation.
+// Initially there are no actions in the history.
+// As each action is performed, it is recorded in the history. The action may either become
+// part of the current user operation or may start a new user operation. If it is to be part of the
+// current operation, then 'mayCoalesce' is true. If it is to be part of a new operation, the
+// 'mayCoalesce' flag of the previous action is set false.
+// The decision of whether to start a new user operation is based upon two factors. If a
+// compound operation has been explicitly started by calling BeginUndoAction and no matching
+// EndUndoAction (these calls nest) has been called, then the action is coalesced into the current
+// operation. If there is no outstanding BeginUndoAction call then a new operation is started
+// unless it looks as if the new action is caused by the user typing or deleting a stream of text.
+// Sequences that look like typing or deletion are coalesced into a single user operation.
+
+int UndoHistory::PreviousAction() const noexcept {
+	return currentAction - 1;
+}
+
+UndoHistory::UndoHistory() {
+	scraps = std::make_unique<ScrapStack>();
+}
+
+UndoHistory::~UndoHistory() noexcept = default;
+
+const char *UndoHistory::AppendAction(ActionType at, Sci::Position position, const char *data, Sci::Position lengthData,
+	bool &startSequence, bool mayCoalesce) {
+	//Platform::DebugPrintf("%% %d action %d %d %d\n", at, position, lengthData, currentAction);
+	//Platform::DebugPrintf("^ %d action %d %d\n", actions[currentAction - 1].at,
+	//	actions[currentAction - 1].position, actions[currentAction - 1].lenData);
+	if (currentAction < savePoint) {
+		savePoint = -1;
+		if (!detach) {
+			detach = currentAction;
+		}
+	} else if (detach && (*detach > currentAction)) {
+		detach = currentAction;
+	}
+	if (undoSequenceDepth > 0) {
+		// Actions not at top level are always coalesced unless this is after return to top level
+		mayCoalesce = true;
+	}
+	bool coalesce = true;
+	if (currentAction >= 1) {
+		int targetAct = currentAction - 1;
+		if (0 == undoSequenceDepth) {
+			// Top level actions may not always be coalesced
+			// Container actions may forward the coalesce state of Scintilla Actions.
+			while ((targetAct > 0) && (actions.types[targetAct].at == ActionType::container) && actions.types[targetAct].mayCoalesce) {
+				targetAct--;
+			}
+			// See if current action can be coalesced into previous action
+			// Will work if both are inserts or deletes and position is same
+			if ((currentAction == savePoint) || (currentAction == tentativePoint)) {
+				coalesce = false;
+			} else if (!mayCoalesce || !actions.types[targetAct].mayCoalesce) {
+				coalesce = false;
+			} else if (at == ActionType::container || actions.types[targetAct].at == ActionType::container) {
+				;	// A coalescible containerAction
+			} else if ((at != actions.types[targetAct].at)) { // } && (!actions.AtStart(targetAct))) {
+				coalesce = false;
+			} else if ((at == ActionType::insert) &&
+			           (position != (actions.positions.SignedValueAt(targetAct) + actions.lengths.SignedValueAt(targetAct)))) {
+				// Insertions must be immediately after to coalesce
+				coalesce = false;
+			} else if (at == ActionType::remove) {
+				if ((lengthData == 1) || (lengthData == 2)) {
+					if ((position + lengthData) == actions.positions.SignedValueAt(targetAct)) {
+						; // Backspace -> OK
+					} else if (position == actions.positions.SignedValueAt(targetAct)) {
+						; // Delete -> OK
+					} else {
+						// Removals must be at same position to coalesce
+						coalesce = false;
+					}
+				} else {
+					// Removals must be of one character to coalesce
+					coalesce = false;
+				}
+			} else {
+				// Action coalesced.
+			}
+
+		} else {
+			// Actions not at top level are always coalesced unless this is after return to top level
+			if (!actions.types[targetAct].mayCoalesce)
+				coalesce = false;
+		}
+	} else {
+		coalesce = false;
+	}
+	startSequence = !coalesce;
+	// Maybe close previous action
+	if ((currentAction > 0) && startSequence) {
+		actions.types[PreviousAction()].mayCoalesce = false;
+	}
+	const char *dataNew = lengthData ? scraps->Push(data, lengthData) : nullptr;
+	if (currentAction >= actions.SSize()) {
+		actions.PushBack();
+	}
+	actions.Create(currentAction, at, position, lengthData, mayCoalesce);
+	currentAction++;
+	return dataNew;
+}
+
+void UndoHistory::BeginUndoAction(bool mayCoalesce) noexcept {
+	if (undoSequenceDepth == 0) {
+		if (currentAction > 0) {
+			actions.types[PreviousAction()].mayCoalesce = mayCoalesce;
+		}
+	}
+	undoSequenceDepth++;
+}
+
+void UndoHistory::EndUndoAction() noexcept {
+	PLATFORM_ASSERT(undoSequenceDepth > 0);
+	undoSequenceDepth--;
+	if (0 == undoSequenceDepth) {
+		if (currentAction > 0) {
+			actions.types[PreviousAction()].mayCoalesce = false;
+		}
+	}
+}
+
+void UndoHistory::DropUndoSequence() noexcept {
+	undoSequenceDepth = 0;
+}
+
+void UndoHistory::DeleteUndoHistory() noexcept {
+	actions.Clear();
+	currentAction = 0;
+	savePoint = 0;
+	tentativePoint = -1;
+	scraps->Clear();
+	memory = {};
+}
+
+int UndoHistory::Actions() const noexcept {
+	return static_cast<int>(actions.SSize());
+}
+
+void UndoHistory::SetSavePoint(int action) noexcept {
+	savePoint = action;
+}
+
+int UndoHistory::SavePoint() const noexcept {
+	return savePoint;
+}
+
+void UndoHistory::SetSavePoint() noexcept {
+	savePoint = currentAction;
+	detach.reset();
+}
+
+bool UndoHistory::IsSavePoint() const noexcept {
+	return savePoint == currentAction;
+}
+
+bool UndoHistory::BeforeSavePoint() const noexcept {
+	return (savePoint < 0) || (savePoint > currentAction);
+}
+
+bool UndoHistory::PreviousBeforeSavePoint() const noexcept {
+	return (savePoint < 0) || (savePoint >= currentAction);
+}
+
+bool UndoHistory::BeforeReachableSavePoint() const noexcept {
+	return (savePoint > 0) && (savePoint > currentAction);
+}
+
+bool UndoHistory::AfterSavePoint() const noexcept {
+	return (savePoint >= 0) && (savePoint <= currentAction);
+}
+
+void UndoHistory::SetDetachPoint(int action) noexcept {
+	if (action == -1) {
+		detach = {};
+	} else {
+		detach = action;
+	}
+}
+
+int UndoHistory::DetachPoint() const noexcept {
+	return detach.value_or(-1);
+}
+
+bool UndoHistory::AfterDetachPoint() const noexcept {
+	return detach && (*detach < currentAction);
+}
+
+bool UndoHistory::AfterOrAtDetachPoint() const noexcept {
+	return detach && (*detach <= currentAction);
+}
+
+intptr_t UndoHistory::Delta(int action) noexcept {
+	intptr_t sizeChange = 0;
+	for (int act = 0; act < action; act++) {
+		const intptr_t lengthChange = actions.lengths.SignedValueAt(act);
+		sizeChange += (actions.types[act].at == ActionType::insert) ? lengthChange : -lengthChange;
+	}
+	return sizeChange;
+}
+
+bool UndoHistory::Validate(intptr_t lengthDocument) noexcept {
+	// Check history for validity
+	const intptr_t sizeChange = Delta(currentAction);
+	if (sizeChange > lengthDocument) {
+		// Current document size too small for changes made in undo history.
+		return false;
+	}
+	const intptr_t lengthOriginal = lengthDocument - sizeChange;
+	intptr_t lengthCurrent = lengthOriginal;
+	for (int act = 0; act < actions.SSize(); act++) {
+		const intptr_t lengthChange = actions.lengths.SignedValueAt(act);
+		if (actions.positions.SignedValueAt(act) > lengthCurrent) {
+			// Change outside document.
+			return false;
+		}
+		lengthCurrent += (actions.types[act].at == ActionType::insert) ? lengthChange : -lengthChange;
+		if (lengthCurrent < 0) {
+			return false;
+		}
+	}
+	return true;
+}
+
+void UndoHistory::SetCurrent(int action, intptr_t lengthDocument) {
+	// Find position in scraps for action
+	memory = {};
+	const size_t lengthSum = actions.LengthTo(action);
+	scraps->SetCurrent(lengthSum);
+	currentAction = action;
+	if (!Validate(lengthDocument)) {
+		currentAction = 0;
+		DeleteUndoHistory();
+		throw std::runtime_error("UndoHistory::SetCurrent: invalid undo history.");
+	}
+}
+
+int UndoHistory::Current() const noexcept {
+	return currentAction;
+}
+
+int UndoHistory::Type(int action) const noexcept {
+	const int baseType = static_cast<int>(actions.types[action].at);
+	const int open = actions.types[action].mayCoalesce ? coalesceFlag : 0;
+	return baseType | open;
+}
+
+Sci::Position UndoHistory::Position(int action) const noexcept {
+	return actions.positions.SignedValueAt(action);
+}
+
+Sci::Position UndoHistory::Length(int action) const noexcept {
+	return actions.lengths.SignedValueAt(action);
+}
+
+std::string_view UndoHistory::Text(int action) noexcept {
+	// Assumes first call after any changes is for action 0.
+	// TODO: may need to invalidate memory in other circumstances
+	if (action == 0) {
+		memory = {};
+	}
+	int act = 0;
+	size_t position = 0;
+	if (memory && memory->act <= action) {
+		act = memory->act;
+		position = memory->position;
+	}
+	for (; act < action; act++) {
+		position += actions.lengths.ValueAt(act);
+	}
+	const size_t length = actions.lengths.ValueAt(action);
+	const char *scrap = scraps->TextAt(position);
+	memory = {action, position};
+	return {scrap, length};
+}
+
+void UndoHistory::PushUndoActionType(int type, Sci::Position position) {
+	actions.PushBack();
+	actions.Create(actions.SSize()-1, static_cast<ActionType>(type & byteMask),
+		position, 0, type & coalesceFlag);
+}
+
+void UndoHistory::ChangeLastUndoActionText(size_t length, const char *text) {
+	assert(actions.lengths.ValueAt(actions.SSize()-1) == 0);
+	actions.lengths.SetValueAt(actions.SSize()-1, length);
+	scraps->Push(text, length);
+}
+
+void UndoHistory::SetTentative(int action) noexcept {
+	tentativePoint = action;
+}
+
+int UndoHistory::TentativePoint() const noexcept {
+	return tentativePoint;
+}
+
+void UndoHistory::TentativeStart() noexcept {
+	tentativePoint = currentAction;
+}
+
+void UndoHistory::TentativeCommit() noexcept {
+	tentativePoint = -1;
+	// Truncate undo history
+	actions.Truncate(currentAction);
+}
+
+bool UndoHistory::TentativeActive() const noexcept {
+	return tentativePoint >= 0;
+}
+
+int UndoHistory::TentativeSteps() const noexcept {
+	// Drop any trailing startAction
+	if (tentativePoint >= 0)
+		return currentAction - tentativePoint;
+	return -1;
+}
+
+bool UndoHistory::CanUndo() const noexcept {
+	return (currentAction > 0) && (actions.SSize() != 0);
+}
+
+int UndoHistory::StartUndo() const noexcept {
+	assert(currentAction >= 0);
+
+	// Count the steps in this action
+	if (currentAction == 0) {
+		return 0;
+	}
+
+	int act = currentAction - 1;
+
+	while (act > 0 && !actions.AtStart(act)) {
+		act--;
+	}
+	return currentAction - act;
+}
+
+Action UndoHistory::GetUndoStep() const noexcept {
+	const int previousAction = PreviousAction();
+	Action acta {
+		actions.types[previousAction].at,
+		actions.types[previousAction].mayCoalesce,
+		actions.positions.SignedValueAt(previousAction),
+		nullptr,
+		actions.lengths.SignedValueAt(previousAction)
+	};
+	if (acta.lenData) {
+		acta.data = scraps->CurrentText() - acta.lenData;
+	}
+	return acta;
+}
+
+void UndoHistory::CompletedUndoStep() noexcept {
+	scraps->MoveBack(actions.lengths.ValueAt(PreviousAction()));
+	currentAction--;
+}
+
+bool UndoHistory::CanRedo() const noexcept {
+	return actions.SSize() > currentAction;
+}
+
+int UndoHistory::StartRedo() const noexcept {
+	// Count the steps in this action
+
+	if (currentAction >= actions.SSize()) {
+		// Already at end so can't redo
+		return 0;
+	}
+
+	// Slightly unusual logic handles case where last action still has mayCoalesce.
+	// Could set mayCoalesce of last action to false in StartUndo but this state is
+	// visible to applications so should not be changed.
+	const int maxAction = Actions() - 1;
+	int act = currentAction;
+	while (act <= maxAction && actions.types[act].mayCoalesce) {
+		act++;
+	}
+	act = std::min(act, maxAction);
+	return act - currentAction + 1;
+}
+
+Action UndoHistory::GetRedoStep() const noexcept {
+	Action acta{
+		actions.types[currentAction].at,
+		actions.types[currentAction].mayCoalesce,
+		actions.positions.SignedValueAt(currentAction),
+		nullptr,
+		actions.lengths.SignedValueAt(currentAction)
+	};
+	if (acta.lenData) {
+		acta.data = scraps->CurrentText();
+	}
+	return acta;
+}
+
+void UndoHistory::CompletedRedoStep() noexcept {
+	scraps->MoveForward(actions.lengths.ValueAt(currentAction));
+	currentAction++;
+}
+
+}
diff --git a/scintilla/src/UndoHistory.h b/scintilla/src/UndoHistory.h
new file mode 100644
index 000000000..8d39a908d
--- /dev/null
+++ b/scintilla/src/UndoHistory.h
@@ -0,0 +1,157 @@
+// Scintilla source code edit control
+/** @file UndoHistory.h
+ ** Manages undo for the document.
+ **/
+// Copyright 1998-2024 by Neil Hodgson <neilh@scintilla.org>
+// The License.txt file describes the conditions under which this software may be distributed.
+
+#ifndef UNDOHISTORY_H
+#define UNDOHISTORY_H
+
+namespace Scintilla::Internal {
+
+// ScaledVector is a vector of unsigned integers that uses elements sized to hold the largest value.
+// Thus, if an undo history only contains short insertions and deletions the lengths vector may
+// only use 2 bytes or even 1 byte for each length.
+// This saves much memory often reducing by 50% for 32-bit builds and 75% for 64-bit builds.
+
+struct SizeMax {
+	size_t size = 1;
+	size_t maxValue = UINT8_MAX;
+};
+
+class ScaledVector {
+	SizeMax element;
+	std::vector<uint8_t> bytes;
+public:
+	[[nodiscard]] size_t Size() const noexcept;
+	[[nodiscard]] size_t ValueAt(size_t index) const noexcept;
+	[[nodiscard]] intptr_t SignedValueAt(size_t index) const noexcept;
+	void SetValueAt(size_t index, size_t value);
+	void ClearValueAt(size_t index) noexcept;
+	void Clear() noexcept;
+	void Truncate(size_t length) noexcept;
+	void ReSize(size_t length);
+	void PushBack();
+
+	// For testing
+	[[nodiscard]] size_t SizeInBytes() const noexcept;
+};
+
+class UndoActionType {
+public:
+	ActionType at : 4;
+	bool mayCoalesce : 1;
+	UndoActionType() noexcept;
+};
+
+struct UndoActions {
+	std::vector<UndoActionType> types;
+	ScaledVector positions;
+	ScaledVector lengths;
+
+	UndoActions() noexcept;
+	void Truncate(size_t length) noexcept;
+	void PushBack();
+	void Clear() noexcept;
+	[[nodiscard]] intptr_t SSize() const noexcept;
+	void Create(size_t index, ActionType at_, Sci::Position position_, Sci::Position lenData_, bool mayCoalesce_);
+	[[nodiscard]] bool AtStart(size_t index) const noexcept;
+	[[nodiscard]] size_t LengthTo(size_t index) const noexcept;
+};
+
+class ScrapStack {
+	std::string stack;
+	size_t current = 0;
+public:
+	void Clear() noexcept;
+	const char *Push(const char *text, size_t length);
+	void SetCurrent(size_t position) noexcept;
+	void MoveForward(size_t length) noexcept;
+	void MoveBack(size_t length) noexcept;
+	[[nodiscard]] const char *CurrentText() const noexcept;
+	[[nodiscard]] const char *TextAt(size_t position) const noexcept;
+};
+
+constexpr int coalesceFlag = 0x100;
+
+/**
+ *
+ */
+class UndoHistory {
+	UndoActions actions;
+	int currentAction = 0;
+	int undoSequenceDepth = 0;
+	int savePoint = 0;
+	int tentativePoint = -1;
+	std::optional<int> detach;	// Never set if savePoint set (>= 0)
+	std::unique_ptr<ScrapStack> scraps;
+	struct actPos { int act; size_t position; };
+	std::optional<actPos> memory;
+
+	int PreviousAction() const noexcept;
+
+public:
+	UndoHistory();
+	~UndoHistory() noexcept;
+
+	const char *AppendAction(ActionType at, Sci::Position position, const char *data, Sci::Position lengthData, bool &startSequence, bool mayCoalesce=true);
+
+	void BeginUndoAction(bool mayCoalesce=false) noexcept;
+	void EndUndoAction() noexcept;
+	void DropUndoSequence() noexcept;
+	void DeleteUndoHistory() noexcept;
+
+	[[nodiscard]] int Actions() const noexcept;
+
+	/// The save point is a marker in the undo stack where the container has stated that
+	/// the buffer was saved. Undo and redo can move over the save point.
+	void SetSavePoint(int action) noexcept;
+	[[nodiscard]] int SavePoint() const noexcept;
+	void SetSavePoint() noexcept;
+	bool IsSavePoint() const noexcept;
+	bool BeforeSavePoint() const noexcept;
+	bool PreviousBeforeSavePoint() const noexcept;
+	bool BeforeReachableSavePoint() const noexcept;
+	bool AfterSavePoint() const noexcept;
+
+	/// The detach point is the last action that was before an inaccessible missing save point.
+	void SetDetachPoint(int action) noexcept;
+	[[nodiscard]] int DetachPoint() const noexcept;
+	bool AfterDetachPoint() const noexcept;
+	bool AfterOrAtDetachPoint() const noexcept;
+
+	[[nodiscard]] intptr_t Delta(int action) noexcept;
+	[[nodiscard]] bool Validate(intptr_t lengthDocument) noexcept;
+	void SetCurrent(int action, intptr_t lengthDocument);
+	[[nodiscard]] int Current() const noexcept;
+	[[nodiscard]] int Type(int action) const noexcept;
+	[[nodiscard]] Sci::Position Position(int action) const noexcept;
+	[[nodiscard]] Sci::Position Length(int action) const noexcept;
+	[[nodiscard]] std::string_view Text(int action) noexcept;
+	void PushUndoActionType(int type, Sci::Position position);
+	void ChangeLastUndoActionText(size_t length, const char *text);
+
+	// Tentative actions are used for input composition so that it can be undone cleanly
+	void SetTentative(int action) noexcept;
+	[[nodiscard]] int TentativePoint() const noexcept;
+	void TentativeStart() noexcept;
+	void TentativeCommit() noexcept;
+	bool TentativeActive() const noexcept;
+	int TentativeSteps() const noexcept;
+
+	/// To perform an undo, StartUndo is called to retrieve the number of steps, then UndoStep is
+	/// called that many times. Similarly for redo.
+	bool CanUndo() const noexcept;
+	int StartUndo() const noexcept;
+	Action GetUndoStep() const noexcept;
+	void CompletedUndoStep() noexcept;
+	bool CanRedo() const noexcept;
+	int StartRedo() const noexcept;
+	Action GetRedoStep() const noexcept;
+	void CompletedRedoStep() noexcept;
+};
+
+}
+
+#endif
diff --git a/scintilla/src/UniConversion.cxx b/scintilla/src/UniConversion.cxx
index 12f4296ab..c733c8a43 100644
--- a/scintilla/src/UniConversion.cxx
+++ b/scintilla/src/UniConversion.cxx
@@ -241,12 +241,12 @@ std::wstring WStringFromUTF8(std::string_view svu8) {
 	if constexpr (sizeof(wchar_t) == 2) {
 		const size_t len16 = UTF16Length(svu8);
 		std::wstring ws(len16, 0);
-		UTF16FromUTF8(svu8, &ws[0], len16);
+		UTF16FromUTF8(svu8, ws.data(), len16);
 		return ws;
 	} else {
 		const size_t len32 = UTF32Length(svu8);
 		std::wstring ws(len32, 0);
-		UTF32FromUTF8(svu8, reinterpret_cast<unsigned int *>(&ws[0]), len32);
+		UTF32FromUTF8(svu8, reinterpret_cast<unsigned int *>(ws.data()), len32);
 		return ws;
 	}
 }
@@ -255,11 +255,10 @@ unsigned int UTF16FromUTF32Character(unsigned int val, wchar_t *tbuf) noexcept {
 	if (val < SUPPLEMENTAL_PLANE_FIRST) {
 		tbuf[0] = static_cast<wchar_t>(val);
 		return 1;
-	} else {
-		tbuf[0] = static_cast<wchar_t>(((val - SUPPLEMENTAL_PLANE_FIRST) >> 10) + SURROGATE_LEAD_FIRST);
-		tbuf[1] = static_cast<wchar_t>((val & 0x3ff) + SURROGATE_TRAIL_FIRST);
-		return 2;
 	}
+	tbuf[0] = static_cast<wchar_t>(((val - SUPPLEMENTAL_PLANE_FIRST) >> 10) + SURROGATE_LEAD_FIRST);
+	tbuf[1] = static_cast<wchar_t>((val & 0x3ff) + SURROGATE_TRAIL_FIRST);
+	return 2;
 }
 
 const unsigned char UTF8BytesOfLead[256] = {
@@ -358,25 +357,28 @@ int UTF8Classify(const unsigned char *us, size_t len) noexcept {
 	return UTF8MaskInvalid | 1;
 }
 
+int UTF8Classify(const char *s, size_t len) noexcept {
+	return UTF8Classify(reinterpret_cast<const unsigned char *>(s), len);
+}
+
 int UTF8DrawBytes(const char *s, size_t len) noexcept {
-	const int utf8StatusNext = UTF8Classify(reinterpret_cast<const unsigned char *>(s), len);
+	const int utf8StatusNext = UTF8Classify(s, len);
 	return (utf8StatusNext & UTF8MaskInvalid) ? 1 : (utf8StatusNext & UTF8MaskWidth);
 }
 
 bool UTF8IsValid(std::string_view svu8) noexcept {
-	const unsigned char *us = reinterpret_cast<const unsigned char *>(svu8.data());
+	const char *s = svu8.data();
 	size_t remaining = svu8.length();
 	while (remaining > 0) {
-		const int utf8Status = UTF8Classify(us, remaining);
+		const int utf8Status = UTF8Classify(s, remaining);
 		if (utf8Status & UTF8MaskInvalid) {
 			return false;
-		} else {
-			const int lenChar = utf8Status & UTF8MaskWidth;
-			us += lenChar;
-			remaining -= lenChar;
 		}
+		const int lenChar = utf8Status & UTF8MaskWidth;
+		s += lenChar;
+		remaining -= lenChar;
 	}
-	return remaining == 0;
+	return true;
 }
 
 // Replace invalid bytes in UTF-8 with the replacement character
@@ -385,7 +387,7 @@ std::string FixInvalidUTF8(const std::string &text) {
 	const char *s = text.c_str();
 	size_t remaining = text.size();
 	while (remaining > 0) {
-		const int utf8Status = UTF8Classify(reinterpret_cast<const unsigned char *>(s), remaining);
+		const int utf8Status = UTF8Classify(s, remaining);
 		if (utf8Status & UTF8MaskInvalid) {
 			// Replacement character 0xFFFD = UTF8:"efbfbd".
 			result.append("\xef\xbf\xbd");
diff --git a/scintilla/src/UniConversion.h b/scintilla/src/UniConversion.h
index 6fbe7f58f..86d9f756a 100644
--- a/scintilla/src/UniConversion.h
+++ b/scintilla/src/UniConversion.h
@@ -44,23 +44,24 @@ inline int UnicodeFromUTF8(const unsigned char *us) noexcept {
 	}
 }
 
-inline constexpr bool UTF8IsTrailByte(unsigned char ch) noexcept {
+constexpr bool UTF8IsTrailByte(unsigned char ch) noexcept {
 	return (ch >= 0x80) && (ch < 0xc0);
 }
 
-inline constexpr bool UTF8IsAscii(unsigned char ch) noexcept {
+constexpr bool UTF8IsAscii(unsigned char ch) noexcept {
 	return ch < 0x80;
 }
 
-inline constexpr bool UTF8IsAscii(char ch) noexcept {
+constexpr bool UTF8IsAscii(char ch) noexcept {
 	const unsigned char uch = ch;
 	return uch < 0x80;
 }
 
 enum { UTF8MaskWidth=0x7, UTF8MaskInvalid=0x8 };
 int UTF8Classify(const unsigned char *us, size_t len) noexcept;
+int UTF8Classify(const char *s, size_t len) noexcept;
 inline int UTF8Classify(std::string_view sv) noexcept {
-	return UTF8Classify(reinterpret_cast<const unsigned char *>(sv.data()), sv.length());
+	return UTF8Classify(sv.data(), sv.length());
 }
 
 // Similar to UTF8Classify but returns a length of 1 for invalid bytes
@@ -70,13 +71,13 @@ int UTF8DrawBytes(const char *s, size_t len) noexcept;
 // Line separator is U+2028 \xe2\x80\xa8
 // Paragraph separator is U+2029 \xe2\x80\xa9
 constexpr int UTF8SeparatorLength = 3;
-inline bool UTF8IsSeparator(const unsigned char *us) noexcept {
+constexpr bool UTF8IsSeparator(const unsigned char *us) noexcept {
 	return (us[0] == 0xe2) && (us[1] == 0x80) && ((us[2] == 0xa8) || (us[2] == 0xa9));
 }
 
 // NEL is U+0085 \xc2\x85
 constexpr int UTF8NELLength = 2;
-inline bool UTF8IsNEL(const unsigned char *us) noexcept {
+constexpr bool UTF8IsNEL(const unsigned char *us) noexcept {
 	return (us[0] == 0xc2) && (us[1] == 0x85);
 }
 
@@ -93,11 +94,11 @@ enum { SURROGATE_TRAIL_FIRST = 0xDC00 };
 enum { SURROGATE_TRAIL_LAST = 0xDFFF };
 enum { SUPPLEMENTAL_PLANE_FIRST = 0x10000 };
 
-inline constexpr unsigned int UTF16CharLength(wchar_t uch) noexcept {
+constexpr unsigned int UTF16CharLength(wchar_t uch) noexcept {
 	return ((uch >= SURROGATE_LEAD_FIRST) && (uch <= SURROGATE_LEAD_LAST)) ? 2 : 1;
 }
 
-inline constexpr unsigned int UTF16LengthFromUTF8ByteCount(unsigned int byteCount) noexcept {
+constexpr unsigned int UTF16LengthFromUTF8ByteCount(unsigned int byteCount) noexcept {
 	return (byteCount < 4) ? 1 : 2;
 }
 
diff --git a/scintilla/test/simpleTests.py b/scintilla/test/simpleTests.py
index d9b553699..0586f62f0 100644
--- a/scintilla/test/simpleTests.py
+++ b/scintilla/test/simpleTests.py
@@ -887,6 +887,82 @@ class TestSimple(unittest.TestCase):
 		self.assertEqual(self.ed.IsRangeWord(6, 7), 0)
 		self.assertEqual(self.ed.IsRangeWord(6, 8), 1)
 
+atInsertion = 0
+atDeletion = 1
+actMayCoalesce = 0x100
+
+class TestUndoSaveRestore(unittest.TestCase):
+
+	def setUp(self):
+		self.xite = Xite.xiteFrame
+		self.ed = self.xite.ed
+		self.ed.ClearAll()
+		self.ed.EmptyUndoBuffer()
+		self.data = b"xy"
+
+	def testSave(self):
+		self.ed.InsertText(0, self.data)
+		self.assertEqual(self.ed.Contents(), b"xy")
+		self.ed.SetSavePoint()
+		self.ed.InsertText(0, self.data)
+		self.assertEqual(self.ed.Contents(), b"xyxy")
+		self.ed.DeleteRange(1, 2)
+		self.assertEqual(self.ed.Contents(), b"xy")
+		self.ed.DeleteRange(1, 1)
+		self.assertEqual(self.ed.Contents(), b"x")
+
+		self.assertEqual(self.ed.UndoActions, 4)
+		self.assertEqual(self.ed.UndoCurrent, 4)
+		self.assertEqual(self.ed.UndoSavePoint, 1)
+		self.assertEqual(self.ed.UndoTentative, -1)
+		self.assertEqual(self.ed.GetUndoActionType(0), atInsertion)
+		self.assertEqual(self.ed.GetUndoActionPosition(0), 0)
+		self.assertEqual(bytes(self.ed.GetUndoActionText(0)), self.data)
+		self.assertEqual(self.ed.GetUndoActionType(1), atInsertion)
+		self.assertEqual(self.ed.GetUndoActionPosition(1), 0)
+		self.assertEqual(bytes(self.ed.GetUndoActionText(1)), self.data)
+		self.assertEqual(self.ed.GetUndoActionType(2), atDeletion + actMayCoalesce)
+		self.assertEqual(self.ed.GetUndoActionPosition(2), 1)
+		self.assertEqual(bytes(self.ed.GetUndoActionText(2)), b'yx')
+		self.assertEqual(self.ed.GetUndoActionType(3), atDeletion + actMayCoalesce)
+		self.assertEqual(self.ed.GetUndoActionPosition(3), 1)
+		self.assertEqual(bytes(self.ed.GetUndoActionText(3)), b'y')
+
+	def testRestore(self):
+		self.ed.InsertText(0, self.data)
+		self.assertEqual(self.ed.Contents(), b"xy")
+		self.ed.EmptyUndoBuffer()
+
+		self.ed.PushUndoActionType(atInsertion, 0)
+		self.ed.ChangeLastUndoActionText(2, b'xy')
+		self.ed.PushUndoActionType(atInsertion, 0)
+		self.ed.ChangeLastUndoActionText(2, b'xy')
+		self.ed.PushUndoActionType(atDeletion + actMayCoalesce, 1)
+		self.ed.ChangeLastUndoActionText(2, b'yx')
+		self.ed.PushUndoActionType(atDeletion + actMayCoalesce, 1)
+		self.ed.ChangeLastUndoActionText(1, b'y')
+		
+		self.assertEqual(self.ed.UndoActions, 4)
+		self.ed.SetUndoCurrent(1)
+		self.ed.SetUndoSavePoint(1)
+		self.ed.SetUndoTentative(-1)
+		
+		self.ed.Undo()
+		self.assertEqual(self.ed.UndoCurrent, 0)
+		self.assertEqual(self.ed.Contents(), b"")
+		self.ed.Redo()
+		self.assertEqual(self.ed.UndoCurrent, 1)
+		self.assertEqual(self.ed.Contents(), b"xy")
+		self.ed.Redo()
+		self.assertEqual(self.ed.UndoCurrent, 2)
+		self.assertEqual(self.ed.Contents(), b"xyxy")
+		self.ed.Redo()	# Does 2 actions due to mayCoalesce
+		self.assertEqual(self.ed.UndoCurrent, 4)
+		self.assertEqual(self.ed.Contents(), b"x")
+
+		# No more redo actions
+		self.assertEqual(self.ed.CanRedo(), 0)
+
 class TestChangeHistory(unittest.TestCase):
 
 	def setUp(self):
diff --git a/scintilla/test/unit/UnitTester.cxx b/scintilla/test/unit/UnitTester.cxx
index 6382b428b..354ae5919 100644
--- a/scintilla/test/unit/UnitTester.cxx
+++ b/scintilla/test/unit/UnitTester.cxx
@@ -16,7 +16,9 @@
 
 #include "Debugging.h"
 
+#if defined(_WIN32)
 #define CATCH_CONFIG_WINDOWS_CRTDBG
+#endif
 #define CATCH_CONFIG_RUNNER
 #include "catch.hpp"
 
diff --git a/scintilla/test/unit/UnitTester.vcxproj b/scintilla/test/unit/UnitTester.vcxproj
index 77b025d64..bb68d374a 100644
--- a/scintilla/test/unit/UnitTester.vcxproj
+++ b/scintilla/test/unit/UnitTester.vcxproj
@@ -165,6 +165,7 @@
     <ClCompile Include="..\..\src\PerLine.cxx" />
     <ClCompile Include="..\..\src\RESearch.cxx" />
     <ClCompile Include="..\..\src\RunStyles.cxx" />
+    <ClCompile Include="..\..\src\UndoHistory.cxx" />
     <ClCompile Include="..\..\src\UniConversion.cxx" />
     <ClCompile Include="..\..\src\UniqueString.cxx" />
     <ClCompile Include="test*.cxx" />
diff --git a/scintilla/test/unit/makefile b/scintilla/test/unit/makefile
index 2e809f422..78484ad9a 100644
--- a/scintilla/test/unit/makefile
+++ b/scintilla/test/unit/makefile
@@ -68,6 +68,7 @@ Geometry.o \
 PerLine.o \
 RESearch.o \
 RunStyles.o \
+UndoHistory.o \
 UniConversion.o \
 UniqueString.o
 
diff --git a/scintilla/test/unit/test.mak b/scintilla/test/unit/test.mak
index 10a6ebac7..e4a448f8c 100644
--- a/scintilla/test/unit/test.mak
+++ b/scintilla/test/unit/test.mak
@@ -25,6 +25,7 @@ TESTEDSRC=\
  ../../src/PerLine.cxx \
  ../../src/RESearch.cxx \
  ../../src/RunStyles.cxx \
+ ../../src/UndoHistory.cxx \
  ../../src/UniConversion.cxx \
  ../../src/UniqueString.cxx
 
diff --git a/scintilla/test/unit/testCellBuffer.cxx b/scintilla/test/unit/testCellBuffer.cxx
index eaa5b0f31..a6bd5dba1 100644
--- a/scintilla/test/unit/testCellBuffer.cxx
+++ b/scintilla/test/unit/testCellBuffer.cxx
@@ -6,6 +6,7 @@
 #include <cassert>
 #include <cstring>
 #include <stdexcept>
+#include <string>
 #include <string_view>
 #include <vector>
 #include <optional>
@@ -23,6 +24,7 @@
 #include "SparseVector.h"
 #include "ChangeHistory.h"
 #include "CellBuffer.h"
+#include "UndoHistory.h"
 
 #include "catch.hpp"
 
@@ -34,6 +36,35 @@ bool Equal(const char *ptr, std::string_view sv) noexcept {
 	return memcmp(ptr, sv.data(), sv.length()) == 0;
 }
 
+TEST_CASE("ScrapStack") {
+
+	ScrapStack ss;
+
+	SECTION("Push") {
+		const char *t = ss.Push("abc", 3);
+		REQUIRE(memcmp(t, "abc", 3) == 0);
+
+		ss.MoveBack(3);
+		const char *text = ss.CurrentText();
+		REQUIRE(memcmp(text, "abc", 3) == 0);
+
+		ss.MoveForward(1);
+		const char *text2 = ss.CurrentText();
+		REQUIRE(memcmp(text2, "bc", 2) == 0);
+
+		ss.SetCurrent(1);
+		const char *text3 = ss.CurrentText();
+		REQUIRE(memcmp(text3, "bc", 2) == 0);
+
+		const char *text4 = ss.TextAt(2);
+		REQUIRE(memcmp(text4, "c", 1) == 0);
+
+		ss.Clear();
+		const char *text5 = ss.Push("1", 1);
+		REQUIRE(memcmp(text5, "1", 1) == 0);
+	}
+}
+
 TEST_CASE("CellBuffer") {
 
 	constexpr std::string_view sText = "Scintilla";
@@ -210,6 +241,408 @@ TEST_CASE("CellBuffer") {
 
 }
 
+bool Equal(const Action &a, ActionType at, Sci::Position position, std::string_view value) noexcept {
+	// Currently ignores mayCoalesce since this is not set consistently when following
+	// start action implies it.
+	if (a.at != at)
+		return false;
+	if (a.position != position)
+		return false;
+	if (a.lenData != static_cast<Sci::Position>(value.length()))
+		return false;
+	if (memcmp(a.data, value.data(), a.lenData) != 0)
+		return false;
+	return true;
+}
+
+bool EqualContainerAction(const Action &a, Sci::Position token) noexcept {
+	// Currently ignores mayCoalesce
+	if (a.at != ActionType::container)
+		return false;
+	if (a.position != token)
+		return false;
+	if (a.lenData != 0)
+		return false;
+	if (a.data)
+		return false;
+	return true;
+}
+
+void TentativeUndo(UndoHistory &uh) noexcept {
+	const int steps = uh.TentativeSteps();
+	for (int step = 0; step < steps; step++) {
+		/* const Action &actionStep = */ uh.GetUndoStep();
+		uh.CompletedUndoStep();
+	}
+	uh.TentativeCommit();
+}
+
+TEST_CASE("ScaledVector") {
+
+	ScaledVector sv;
+	
+	SECTION("ScalingUp") {
+		sv.ReSize(1);
+		REQUIRE(sv.SizeInBytes() == 1);
+		REQUIRE(sv.ValueAt(0) == 0);
+		sv.SetValueAt(0, 1);
+		REQUIRE(sv.ValueAt(0) == 1);
+		REQUIRE(sv.SignedValueAt(0) == 1);
+		sv.ClearValueAt(0);
+		REQUIRE(sv.ValueAt(0) == 0);
+
+		// Check boundary of 1-byte values
+		sv.SetValueAt(0, 0xff);
+		REQUIRE(sv.ValueAt(0) == 0xff);
+		REQUIRE(sv.SizeInBytes() == 1);
+		// Require expansion to 2 byte elements
+		sv.SetValueAt(0, 0x100);
+		REQUIRE(sv.ValueAt(0) == 0x100);
+		REQUIRE(sv.SizeInBytes() == 2);
+		// Only ever expands, never diminishes element size
+		sv.SetValueAt(0, 0xff);
+		REQUIRE(sv.ValueAt(0) == 0xff);
+		REQUIRE(sv.SizeInBytes() == 2);
+
+		// Check boundary of 2-byte values
+		sv.SetValueAt(0, 0xffff);
+		REQUIRE(sv.ValueAt(0) == 0xffff);
+		REQUIRE(sv.SizeInBytes() == 2);
+		// Require expansion to 2 byte elements
+		sv.SetValueAt(0, 0x10000);
+		REQUIRE(sv.ValueAt(0) == 0x10000);
+		REQUIRE(sv.SizeInBytes() == 3);
+
+		// Check that its not just simple bit patterns that work
+		sv.SetValueAt(0, 0xd4381);
+		REQUIRE(sv.ValueAt(0) == 0xd4381);
+
+		// Add a second item
+		sv.ReSize(2);
+		REQUIRE(sv.SizeInBytes() == 6);
+		// Truncate
+		sv.Truncate(1);
+		REQUIRE(sv.SizeInBytes() == 3);
+		REQUIRE(sv.ValueAt(0) == 0xd4381);
+
+		sv.Clear();
+		REQUIRE(sv.Size() == 0);
+		sv.PushBack();
+		REQUIRE(sv.Size() == 1);
+		REQUIRE(sv.SizeInBytes() == 3);
+		sv.SetValueAt(0, 0x1fd4381);
+		REQUIRE(sv.SizeInBytes() == 4);
+		REQUIRE(sv.ValueAt(0) == 0x1fd4381);
+	}
+}
+
+TEST_CASE("UndoHistory") {
+
+	UndoHistory uh;
+
+	SECTION("Basics") {
+		REQUIRE(uh.IsSavePoint());
+		REQUIRE(uh.AfterSavePoint());
+		REQUIRE(!uh.BeforeSavePoint());
+		REQUIRE(!uh.BeforeReachableSavePoint());
+		REQUIRE(!uh.CanUndo());
+		REQUIRE(!uh.CanRedo());
+
+		bool startSequence = false;
+		const char *val = uh.AppendAction(ActionType::insert, 0, "ab", 2, startSequence, true);
+		REQUIRE(memcmp(val, "ab", 2) == 0);
+		REQUIRE(startSequence);
+		REQUIRE(!uh.IsSavePoint());
+		REQUIRE(uh.AfterSavePoint());
+		REQUIRE(uh.CanUndo());
+		REQUIRE(!uh.CanRedo());
+		val = uh.AppendAction(ActionType::remove, 0, "ab", 2, startSequence, true);
+		REQUIRE(memcmp(val, "ab", 2) == 0);
+		REQUIRE(startSequence);
+
+		// Undoing
+		{
+			const int steps = uh.StartUndo();
+			REQUIRE(steps == 1);
+			const Action action = uh.GetUndoStep();
+			REQUIRE(Equal(action, ActionType::remove, 0, "ab"));
+			uh.CompletedUndoStep();
+		}
+		{
+			const int steps = uh.StartUndo();
+			REQUIRE(steps == 1);
+			const Action action = uh.GetUndoStep();
+			REQUIRE(Equal(action, ActionType::insert, 0, "ab"));
+			uh.CompletedUndoStep();
+		}
+
+		REQUIRE(uh.IsSavePoint());
+
+		// Redoing
+		{
+			const int steps = uh.StartRedo();
+			REQUIRE(steps == 1);
+			const Action action = uh.GetRedoStep();
+			REQUIRE(Equal(action, ActionType::insert, 0, "ab"));
+			uh.CompletedRedoStep();
+		}
+		{
+			const int steps = uh.StartRedo();
+			REQUIRE(steps == 1);
+			const Action action = uh.GetRedoStep();
+			REQUIRE(Equal(action, ActionType::remove, 0, "ab"));
+			uh.CompletedRedoStep();
+		}
+
+		REQUIRE(!uh.IsSavePoint());
+	}
+
+	SECTION("Coalesce") {
+
+		bool startSequence = false;
+		const char *val = uh.AppendAction(ActionType::insert, 0, "ab", 2, startSequence, true);
+		REQUIRE(memcmp(val, "ab", 2) == 0);
+		REQUIRE(startSequence);
+		REQUIRE(!uh.IsSavePoint());
+		REQUIRE(uh.AfterSavePoint());
+		REQUIRE(uh.CanUndo());
+		REQUIRE(!uh.CanRedo());
+		val = uh.AppendAction(ActionType::insert, 2, "cd", 2, startSequence, true);
+		REQUIRE(memcmp(val, "cd", 2) == 0);
+		REQUIRE(!startSequence);
+
+		// Undoing
+		{
+			const int steps = uh.StartUndo();
+			REQUIRE(steps == 2);
+			const Action action2 = uh.GetUndoStep();
+			REQUIRE(Equal(action2, ActionType::insert, 2, "cd"));
+			uh.CompletedUndoStep();
+			const Action action1 = uh.GetUndoStep();
+			REQUIRE(Equal(action1, ActionType::insert, 0, "ab"));
+			uh.CompletedUndoStep();
+		}
+
+		REQUIRE(uh.IsSavePoint());
+
+		// Redoing
+		{
+			const int steps = uh.StartRedo();
+			REQUIRE(steps == 2);
+			const Action action1 = uh.GetRedoStep();
+			REQUIRE(Equal(action1, ActionType::insert, 0, "ab"));
+			uh.CompletedRedoStep();
+			const Action action2 = uh.GetRedoStep();
+			REQUIRE(Equal(action2, ActionType::insert, 2, "cd"));
+			uh.CompletedRedoStep();
+		}
+
+		REQUIRE(!uh.IsSavePoint());
+
+	}
+
+	SECTION("SimpleContainer") {
+		bool startSequence = false;
+		const char *val = uh.AppendAction(ActionType::container, 1000, nullptr, 0, startSequence, true);
+		REQUIRE(startSequence);
+		REQUIRE(!val);
+		val = uh.AppendAction(ActionType::container, 1001, nullptr, 0, startSequence, true);
+		REQUIRE(!startSequence);
+		REQUIRE(!val);
+	}
+
+	SECTION("CoalesceContainer") {
+		bool startSequence = false;
+		const char *val = uh.AppendAction(ActionType::insert, 0, "ab", 2, startSequence, true);
+		REQUIRE(memcmp(val, "ab", 2) == 0);
+		REQUIRE(startSequence);
+		val = uh.AppendAction(ActionType::container, 1000, nullptr, 0, startSequence, true);
+		REQUIRE(!startSequence);
+		// container actions do not have text data, just the token store in position
+		REQUIRE(!val);
+		uh.AppendAction(ActionType::container, 1001, nullptr, 0, startSequence, true);
+		REQUIRE(!startSequence);
+		// This is a coalescible change since the container actions are skipped to determine compatibility
+		val = uh.AppendAction(ActionType::insert, 2, "cd", 2, startSequence, true);
+		REQUIRE(memcmp(val, "cd", 2) == 0);
+		REQUIRE(!startSequence);
+		// Break the sequence with a non-coalescible container action
+		uh.AppendAction(ActionType::container, 1002, nullptr, 0, startSequence, false);
+		REQUIRE(startSequence);
+
+		{
+			const int steps = uh.StartUndo();
+			REQUIRE(steps == 1);
+			const Action actionContainer = uh.GetUndoStep();
+			REQUIRE(EqualContainerAction(actionContainer, 1002));
+			REQUIRE(actionContainer.mayCoalesce == false);
+			uh.CompletedUndoStep();
+		}
+		{
+			const int steps = uh.StartUndo();
+			REQUIRE(steps == 4);
+			const Action actionInsert = uh.GetUndoStep();
+			REQUIRE(Equal(actionInsert, ActionType::insert, 2, "cd"));
+			uh.CompletedUndoStep();
+			{
+				const Action actionContainer = uh.GetUndoStep();
+				REQUIRE(EqualContainerAction(actionContainer, 1001));
+				uh.CompletedUndoStep();
+			}
+			{
+				const Action actionContainer = uh.GetUndoStep();
+				REQUIRE(EqualContainerAction(actionContainer, 1000));
+				uh.CompletedUndoStep();
+			}
+			{
+				const Action actionInsert1 = uh.GetUndoStep();
+				REQUIRE(Equal(actionInsert1, ActionType::insert, 0, "ab"));
+				uh.CompletedUndoStep();
+			}
+		}
+		// Reached beginning
+		REQUIRE(!uh.CanUndo());
+	}
+
+	SECTION("Grouping") {
+
+		uh.BeginUndoAction();
+
+		bool startSequence = false;
+		const char *val = uh.AppendAction(ActionType::insert, 0, "ab", 2, startSequence, true);
+		REQUIRE(memcmp(val, "ab", 2) == 0);
+		REQUIRE(startSequence);
+		REQUIRE(!uh.IsSavePoint());
+		REQUIRE(uh.AfterSavePoint());
+		REQUIRE(uh.CanUndo());
+		REQUIRE(!uh.CanRedo());
+		val = uh.AppendAction(ActionType::remove, 0, "ab", 2, startSequence, true);
+		REQUIRE(memcmp(val, "ab", 2) == 0);
+		REQUIRE(!startSequence);
+		val = uh.AppendAction(ActionType::insert, 0, "cde", 3, startSequence, true);
+		REQUIRE(memcmp(val, "cde", 3) == 0);
+		REQUIRE(!startSequence);
+
+		uh.EndUndoAction();
+
+		// Undoing
+		{
+			const int steps = uh.StartUndo();
+			REQUIRE(steps == 3);
+			const Action action3 = uh.GetUndoStep();
+			REQUIRE(Equal(action3, ActionType::insert, 0, "cde"));
+			uh.CompletedUndoStep();
+			const Action action2 = uh.GetUndoStep();
+			REQUIRE(Equal(action2, ActionType::remove, 0, "ab"));
+			uh.CompletedUndoStep();
+			const Action action1 = uh.GetUndoStep();
+			REQUIRE(Equal(action1, ActionType::insert, 0, "ab"));
+			uh.CompletedUndoStep();
+		}
+
+		REQUIRE(uh.IsSavePoint());
+
+		// Redoing
+		{
+			const int steps = uh.StartRedo();
+			REQUIRE(steps == 3);
+			const Action action1 = uh.GetRedoStep();
+			REQUIRE(Equal(action1, ActionType::insert, 0, "ab"));
+			uh.CompletedRedoStep();
+			const Action action2 = uh.GetRedoStep();
+			REQUIRE(Equal(action2, ActionType::remove, 0, "ab"));
+			uh.CompletedRedoStep();
+			const Action action3 = uh.GetRedoStep();
+			REQUIRE(Equal(action3, ActionType::insert, 0, "cde"));
+			uh.CompletedRedoStep();
+		}
+
+		REQUIRE(!uh.IsSavePoint());
+
+	}
+
+	SECTION("DeepGroup") {
+
+		uh.BeginUndoAction();
+		uh.BeginUndoAction();
+
+		bool startSequence = false;
+		const char *val = uh.AppendAction(ActionType::insert, 0, "ab", 2, startSequence, true);
+		REQUIRE(memcmp(val, "ab", 2) == 0);
+		REQUIRE(startSequence);
+		val = uh.AppendAction(ActionType::container, 1000, nullptr, 0, startSequence, false);
+		REQUIRE(!val);
+		REQUIRE(!startSequence);
+		val = uh.AppendAction(ActionType::remove, 0, "ab", 2, startSequence, true);
+		REQUIRE(memcmp(val, "ab", 2) == 0);
+		REQUIRE(!startSequence);
+		val = uh.AppendAction(ActionType::insert, 0, "cde", 3, startSequence, true);
+		REQUIRE(memcmp(val, "cde", 3) == 0);
+		REQUIRE(!startSequence);
+
+		uh.EndUndoAction();
+		uh.EndUndoAction();
+
+		const int steps = uh.StartUndo();
+		REQUIRE(steps == 4);
+	}
+
+	SECTION("Tentative") {
+
+		REQUIRE(!uh.TentativeActive());
+		REQUIRE(uh.TentativeSteps() == -1);
+		uh.TentativeStart();
+		REQUIRE(uh.TentativeActive());
+		REQUIRE(uh.TentativeSteps() == 0);
+		bool startSequence = false;
+		uh.AppendAction(ActionType::insert, 0, "ab", 2, startSequence, true);
+		REQUIRE(uh.TentativeActive());
+		REQUIRE(uh.TentativeSteps() == 1);
+		REQUIRE(uh.CanUndo());
+		uh.TentativeCommit();
+		REQUIRE(!uh.TentativeActive());
+		REQUIRE(uh.TentativeSteps() == -1);
+		REQUIRE(uh.CanUndo());
+
+		// TentativeUndo is the other important operation but it is performed by Document so add a local equivalent
+		uh.TentativeStart();
+		uh.AppendAction(ActionType::remove, 0, "ab", 2, startSequence, false);
+		uh.AppendAction(ActionType::insert, 0, "ab", 2, startSequence, true);
+		REQUIRE(uh.TentativeActive());
+		// The first TentativeCommit didn't seal off the first action so it is still undoable
+		REQUIRE(uh.TentativeSteps() == 2);
+		REQUIRE(uh.CanUndo());
+		TentativeUndo(uh);
+		REQUIRE(!uh.TentativeActive());
+		REQUIRE(uh.TentativeSteps() == -1);
+		REQUIRE(uh.CanUndo());
+	}
+}
+
+TEST_CASE("UndoActions") {
+
+	UndoActions ua;
+
+	SECTION("Basics") {
+		ua.PushBack();
+		REQUIRE(ua.SSize() == 1);
+		ua.Create(0, ActionType::insert, 0, 2, false);
+		REQUIRE(ua.AtStart(0));
+		REQUIRE(ua.LengthTo(0) == 0);
+		REQUIRE(ua.AtStart(1));
+		REQUIRE(ua.LengthTo(1) == 2);
+		ua.PushBack();
+		REQUIRE(ua.SSize() == 2);
+		ua.Create(0, ActionType::insert, 0, 2, false);
+		REQUIRE(ua.SSize() == 2);
+		ua.Truncate(1);
+		REQUIRE(ua.SSize() == 1);
+		ua.Clear();
+		REQUIRE(ua.SSize() == 0);
+	}
+}
+
+
 TEST_CASE("CharacterIndex") {
 
 	CellBuffer cb(true, false);
@@ -693,20 +1126,20 @@ TEST_CASE("ChangeHistory") {
 
 	SECTION("Delete Contiguous Backward") {
 		// Deletes that touch
-		constexpr size_t length = 20;
-		constexpr size_t rounds = 8;
+		constexpr Sci::Position length = 20;
+		constexpr Sci::Position rounds = 8;
 		il.Insert(0, length, false, true);
 		REQUIRE(il.Length() == length);
 		il.SetSavePoint();
-		for (size_t i = 0; i < rounds; i++) {
+		for (Sci::Position i = 0; i < rounds; i++) {
 			il.DeleteRangeSavingHistory(9-i, 1, false, false);
 		}
 
-		constexpr size_t lengthAfterDeletions = length - rounds;
+		constexpr Sci::Position lengthAfterDeletions = length - rounds;
 		REQUIRE(il.Length() == lengthAfterDeletions);
 		REQUIRE(il.DeletionCount(0, lengthAfterDeletions) == rounds);
 
-		for (size_t j = 0; j < rounds; j++) {
+		for (Sci::Position j = 0; j < rounds; j++) {
 			il.UndoDeleteStep(2+j, 1, false);
 		}
 
@@ -1060,6 +1493,80 @@ TEST_CASE("CellBufferWithChangeHistory") {
 
 namespace {
 
+void PushUndoAction(CellBuffer &cb, int type, Sci::Position pos, std::string_view sv) {
+	cb.PushUndoActionType(type, pos);
+	cb.ChangeLastUndoActionText(sv.length(), sv.data());
+}
+
+}
+
+TEST_CASE("CellBufferLoadUndoHistory") {
+
+	CellBuffer cb(false, false);
+	constexpr int remove = 1;
+	constexpr int insert = 0;
+
+	SECTION("Basics") {
+		cb.SetUndoCollection(false);
+		constexpr std::string_view sInsert = "abcdef";
+		bool startSequence = false;
+		cb.InsertString(0, sInsert.data(), sInsert.length(), startSequence);
+		cb.SetUndoCollection(true);
+		cb.ChangeHistorySet(true);
+
+		// Create an undo history that matches the contents at current point 2
+		// So, 2 actions; current point; 2 actions
+		// a_cdef
+		PushUndoAction(cb, remove, 1, "_");
+		// acdef
+		PushUndoAction(cb, insert, 1, "b");
+		// abcdef -> current
+		PushUndoAction(cb, remove, 3, "d");
+		// abcef -> save
+		PushUndoAction(cb, insert, 3, "*");
+		// abc*ef
+		cb.SetUndoSavePoint(3);
+		cb.SetUndoDetach(-1);
+		cb.SetUndoTentative(-1);
+		cb.SetUndoCurrent(2);
+
+		// 2nd insertion is removed from change history as it isn't visible and isn't saved
+		// 2nd deletion is visible (as insertion) as it was saved but then reverted to original
+		// 1st insertion and 1st deletion are both visible as saved
+		const History hist{ {{1, 1, changeSaved}, {3, 1, changeRevertedOriginal}}, {{2, changeSaved}} };
+		REQUIRE(HistoryOf(cb) == hist);
+	}
+
+	SECTION("Detached") {
+		cb.SetUndoCollection(false);
+		constexpr std::string_view sInsert = "a-b=cdef";
+		bool startSequence = false;
+		cb.InsertString(0, sInsert.data(), sInsert.length(), startSequence);
+		cb.SetUndoCollection(true);
+		cb.ChangeHistorySet(true);
+
+		// Create an undo history that matches the contents at current point 2 which detached at 1
+		// So, insert saved; insert detached; current point
+		// abcdef
+		PushUndoAction(cb, insert, 1, "-");
+		// a-bcdef
+		PushUndoAction(cb, insert, 3, "=");
+		// a-b=cdef
+		cb.SetUndoSavePoint(-1);
+		cb.SetUndoDetach(1);
+		cb.SetUndoTentative(-1);
+		cb.SetUndoCurrent(2);
+
+		// This doesn't show elements due to undo.
+		// There was also a modified delete (reverting the insert) at 3 in the original but that is missing.
+		const History hist{ {{1, 1, changeSaved}, {3, 1, changeModified}}, {} };
+		REQUIRE(HistoryOf(cb) == hist);
+	}
+
+}
+
+namespace {
+
 // Implement low quality reproducible pseudo-random numbers.
 // Pseudo-random algorithm based on R. G. Dromey "How to Solve it by Computer" page 122.
 
@@ -1086,11 +1593,11 @@ TEST_CASE("CellBufferLong") {
 
 	SECTION("Random") {
 		RandomSequence rseq;
-		for (size_t i = 0l; i < 20000; i++) {
+		for (size_t i = 0; i < 20000; i++) {
 			const int r = rseq.Next() % 10;
 			if (r <= 2) {			// 30%
 				// Insert text
-				const int pos = rseq.Next() % (cb.Length() + 1);
+				const Sci::Position pos = rseq.Next() % (cb.Length() + 1);
 				const int len = rseq.Next() % 10 + 1;
 				std::string sInsert;
 				for (int j = 0; j < len; j++) {
@@ -1121,4 +1628,4 @@ TEST_CASE("CellBufferLong") {
 		}
 	}
 }
-#endif
\ No newline at end of file
+#endif
diff --git a/scintilla/test/unit/testCharClassify.cxx b/scintilla/test/unit/testCharClassify.cxx
index 973aeabaf..4329dbd20 100644
--- a/scintilla/test/unit/testCharClassify.cxx
+++ b/scintilla/test/unit/testCharClassify.cxx
@@ -22,8 +22,6 @@ using namespace Scintilla::Internal;
 // Test CharClassify.
 
 class CharClassifyTest {
-	// Avoid warnings, deleted so never called.
-	CharClassifyTest(const CharClassifyTest &) = delete;
 protected:
 	CharClassifyTest() {
 		pcc = std::make_unique<CharClassify>();
@@ -38,11 +36,13 @@ protected:
 				charClass[ch] = CharacterClass::punctuation;
 		}
 	}
+	// Avoid warnings, deleted so never called.
+	CharClassifyTest(const CharClassifyTest &) = delete;
 
 	std::unique_ptr<CharClassify> pcc;
-	CharacterClass charClass[256];
+	CharacterClass charClass[256] {};
 
-	static const char* GetClassName(CharacterClass charClass) {
+	static const char* GetClassName(CharacterClass charClass) noexcept {
 		switch(charClass) {
 			#define CASE(c) case CharacterClass::c: return #c
 			CASE(space);
@@ -70,7 +70,7 @@ TEST_CASE_METHOD(CharClassifyTest, "Defaults") {
 TEST_CASE_METHOD(CharClassifyTest, "Custom") {
 	unsigned char buf[2] = {0, 0};
 	for (int i = 0; i < 256; i++) {
-		CharacterClass thisClass = CharacterClass(i % 4);
+		const CharacterClass thisClass = static_cast<CharacterClass>(i % 4);
 		buf[0] = i;
 		pcc->SetCharClasses(buf, thisClass);
 		charClass[i] = thisClass;
@@ -88,16 +88,16 @@ TEST_CASE_METHOD(CharClassifyTest, "Custom") {
 TEST_CASE_METHOD(CharClassifyTest, "CharsOfClass") {
 	unsigned char buf[2] = {0, 0};
 	for (int i = 1; i < 256; i++) {
-		CharacterClass thisClass = CharacterClass(i % 4);
+		const CharacterClass thisClass = static_cast<CharacterClass>(i % 4);
 		buf[0] = i;
 		pcc->SetCharClasses(buf, thisClass);
 		charClass[i] = thisClass;
 	}
 	for (int classVal = 0; classVal < 4; ++classVal) {
-		CharacterClass thisClass = CharacterClass(classVal % 4);
-		int size = pcc->GetCharsOfClass(thisClass, NULL);
+		const CharacterClass thisClass = static_cast<CharacterClass>(classVal % 4);
+		const int size = pcc->GetCharsOfClass(thisClass, nullptr);
 		std::vector<unsigned char> buffer(size+1);
-		void *pBuffer = static_cast<void *>(buffer.data());
+		const unsigned char *pBuffer = buffer.data();
 		pcc->GetCharsOfClass(thisClass, buffer.data());
 		for (int i = 1; i < 256; i++) {
 			if (charClass[i] == thisClass) {
diff --git a/scintilla/test/unit/testCharacterCategoryMap.cxx b/scintilla/test/unit/testCharacterCategoryMap.cxx
index 8c5305cc7..cdc810b02 100644
--- a/scintilla/test/unit/testCharacterCategoryMap.cxx
+++ b/scintilla/test/unit/testCharacterCategoryMap.cxx
@@ -24,7 +24,7 @@ using namespace Scintilla::Internal;
 
 TEST_CASE("CharacterCategoryMap") {
 
-	CharacterCategoryMap ccm;
+	const CharacterCategoryMap ccm;
 
 	SECTION("LowerCaseLetter") {
 		const CharacterCategory cc = ccm.CategoryFor('a');
diff --git a/scintilla/test/unit/testDocument.cxx b/scintilla/test/unit/testDocument.cxx
index a3fca9f5e..3266b0a9d 100644
--- a/scintilla/test/unit/testDocument.cxx
+++ b/scintilla/test/unit/testDocument.cxx
@@ -57,7 +57,7 @@ struct Folding {
 };
 
 // Table of case folding for non-ASCII bytes in Windows Latin code page 1252
-Folding foldings1252[] = {
+const Folding foldings1252[] = {
 	{0x8a, 0x9a, 0x01},
 	{0x8c, 0x9c, 0x01},
 	{0x8e, 0x9e, 0x01},
@@ -67,7 +67,7 @@ Folding foldings1252[] = {
 };
 
 // Table of case folding for non-ASCII bytes in Windows Russian code page 1251
-Folding foldings1251[] = {
+const Folding foldings1251[] = {
 	{0x80, 0x90, 0x01},
 	{0x81, 0x83, 0x01},
 	{0x8a, 0x9a, 0x01},
@@ -83,7 +83,7 @@ Folding foldings1251[] = {
 	{0xc0, 0xe0, 0x20},
 };
 
-std::string ReadFile(std::string path) {
+std::string ReadFile(const std::string &path) {
 	std::ifstream ifs(path, std::ios::binary);
 	std::string content((std::istreambuf_iterator<char>(ifs)),
 		(std::istreambuf_iterator<char>()));
@@ -164,6 +164,13 @@ struct DocPlus {
 		// Remove insertion
 		document.DeleteChars(gapNew, 1);
 	}
+
+	[[nodiscard]] std::string Contents() const {
+		const Sci::Position length = document.Length();
+		std::string contents(length, 0);
+		document.GetCharRange(contents.data(), 0, length);
+		return contents;
+	}
 };
 
 void TimeTrace(std::string_view sv, const Catch::Timer &tikka) {
@@ -266,7 +273,7 @@ TEST_CASE("Document") {
 		DocPlus doc("_abcdef", 0);	// _ a b c d e f
 		constexpr std::string_view finding = "cd";
 		Sci::Position lengthFinding = finding.length();
-		size_t docLength = doc.document.Length() - 1;
+		const size_t docLength = doc.document.Length() - 1;
 		Sci::Position location = doc.document.FindText(1, docLength, finding.data(), FindOption::MatchCase, &lengthFinding);
 		REQUIRE(location == 3);
 		location = doc.document.FindText(docLength, 1, finding.data(), FindOption::MatchCase, &lengthFinding);
@@ -723,6 +730,80 @@ TEST_CASE("Document") {
 
 }
 
+TEST_CASE("DocumentUndo") {
+
+	// These tests check that Undo reports the end of coalesced deletes
+
+	constexpr std::string_view sText = "Scintilla";
+	DocPlus doc(sText, 0);
+
+	SECTION("CheckDeleteForwards") {
+		// Delete forwards like the Del key
+		doc.document.DeleteUndoHistory();
+		doc.document.DeleteChars(1, 1);
+		doc.document.DeleteChars(1, 1);
+		doc.document.DeleteChars(1, 1);
+		const Sci::Position position = doc.document.Undo();
+		REQUIRE(position == 4);	// End of reinsertion
+		REQUIRE(!doc.document.CanUndo());	// Exhausted undo stack
+		REQUIRE(doc.document.CanRedo());
+	}
+
+	SECTION("CheckDeleteBackwards") {
+		// Delete backwards like the backspace key
+		doc.document.DeleteUndoHistory();
+		doc.document.DeleteChars(5, 1);
+		doc.document.DeleteChars(4, 1);
+		doc.document.DeleteChars(3, 1);
+		const Sci::Position position = doc.document.Undo();
+		REQUIRE(position == 6);	// End of reinsertion
+		REQUIRE(!doc.document.CanUndo());	// Exhausted undo stack
+	}
+
+	SECTION("CheckBothWays") {
+		// Delete backwards like the backspace key
+		doc.document.DeleteUndoHistory();
+		// Like having the caret at position 5 then
+		doc.document.DeleteChars(5, 1);	// Del
+		doc.document.DeleteChars(4, 1); // Backspace
+		doc.document.DeleteChars(4, 1); // Del
+		doc.document.DeleteChars(3, 1); // Backspace
+		const Sci::Position position = doc.document.Undo();
+		REQUIRE(position == 7);	// End of reinsertion, Start at 5, 2*Del
+		REQUIRE(!doc.document.CanUndo());	// Exhausted undo stack
+	}
+
+	SECTION("CheckInsert") {
+		// Insertions are only coalesced when following previous
+		doc.document.DeleteUndoHistory();
+		doc.document.InsertString(1, "1");
+		doc.document.InsertString(2, "2");
+		doc.document.InsertString(3, "3");
+		REQUIRE(doc.Contents() == "S123cintilla");
+		const Sci::Position position = doc.document.Undo();
+		REQUIRE(position == 1);	// Start of insertions
+		REQUIRE(!doc.document.CanUndo());	// Exhausted undo stack
+	}
+
+	SECTION("CheckGrouped") {
+		// Check that position returned for group is that at end of first deletion set
+		// Also include a container undo action.
+		doc.document.DeleteUndoHistory();
+		doc.document.BeginUndoAction();
+		// At 1, 2*Del so end of initial deletion sequence is 3
+		doc.document.DeleteChars(1, 1); // 'c'
+		doc.document.DeleteChars(1, 1); // 'i'
+		doc.document.AddUndoAction(99, true);
+		doc.document.InsertString(1, "1");
+		doc.document.DeleteChars(4, 2); // 'il'
+		doc.document.BeginUndoAction();
+		REQUIRE(doc.Contents() == "S1ntla");
+		const Sci::Position position = doc.document.Undo();
+		REQUIRE(position == 3);	// Start of insertions
+		REQUIRE(!doc.document.CanUndo());	// Exhausted undo stack
+	}
+}
+
 TEST_CASE("Words") {
 
 	SECTION("WordsInText") {
@@ -759,7 +840,7 @@ TEST_CASE("SafeSegment") {
 		const DocPlus doc("", 0);
 		// all encoding: break before or after last space
 		constexpr std::string_view text = "12 ";
-		size_t length = doc.document.SafeSegment(text);
+		const size_t length = doc.document.SafeSegment(text);
 		REQUIRE(length <= text.length());
 		REQUIRE(text[length - 1] == '2');
 		REQUIRE(text[length] == ' ');
diff --git a/scintilla/test/unit/testPartitioning.cxx b/scintilla/test/unit/testPartitioning.cxx
index 8bfc47d39..525dca789 100644
--- a/scintilla/test/unit/testPartitioning.cxx
+++ b/scintilla/test/unit/testPartitioning.cxx
@@ -34,13 +34,13 @@ TEST_CASE("CompileCopying Partitioning") {
 		Partitioning<int> s2;
 
 		// Copy constructor
-		Partitioning<int> sa(s);
+		const Partitioning<int> sa(s);
 		// Copy assignment
 		Partitioning<int> sb;
 		sb = s;
 
 		// Move constructor
-		Partitioning<int> sc(std::move(s));
+		const Partitioning<int> sc(std::move(s));
 		// Move assignment
 		Partitioning<int> sd;
 		sd = (std::move(s2));
diff --git a/scintilla/test/unit/testPerLine.cxx b/scintilla/test/unit/testPerLine.cxx
index d9cf11ac6..47a60ce90 100644
--- a/scintilla/test/unit/testPerLine.cxx
+++ b/scintilla/test/unit/testPerLine.cxx
@@ -41,13 +41,13 @@ TEST_CASE("CompileCopying MarkerHandleSet") {
 		MarkerHandleSet s2;
 
 		// Copy constructor
-		MarkerHandleSet sa(s);
+		const MarkerHandleSet sa(s);
 		// Copy assignment
 		MarkerHandleSet sb;
 		sb = s;
 
 		// Move constructor
-		MarkerHandleSet sc(std::move(s));
+		const MarkerHandleSet sc(std::move(s));
 		// Move assignment
 		MarkerHandleSet sd;
 		sd = (std::move(s2));
diff --git a/scintilla/test/unit/testRESearch.cxx b/scintilla/test/unit/testRESearch.cxx
index 1902fdb2b..4e041d47c 100644
--- a/scintilla/test/unit/testRESearch.cxx
+++ b/scintilla/test/unit/testRESearch.cxx
@@ -33,9 +33,10 @@ using namespace Scintilla::Internal;
 class StringCI : public CharacterIndexer {
 	std::string s;
 public:
-	StringCI(std::string_view sv_) : s(sv_) {
+	explicit StringCI(std::string_view sv_) : s(sv_) {
 	}
-	Sci::Position Length() const noexcept {
+	virtual ~StringCI() = default;
+	[[nodiscard]] Sci::Position Length() const noexcept {
 		return s.length();
 	}
 	char CharAt(Sci::Position index) const override {
@@ -44,7 +45,7 @@ public:
 	Sci::Position MovePositionOutsideChar(Sci::Position pos, [[maybe_unused]] Sci::Position moveDir) const noexcept override {
 		return pos;
 	}
-	std::string GetCharRange(Sci::Position position, Sci::Position lengthRetrieve) const {
+	[[nodiscard]] std::string GetCharRange(Sci::Position position, Sci::Position lengthRetrieve) const {
 		return s.substr(position, lengthRetrieve);
 	}
 };
@@ -58,38 +59,38 @@ TEST_CASE("RESearch") {
 	constexpr std::string_view pattern = "[a-z]+";
 
 	SECTION("Compile") {
-		std::unique_ptr<RESearch> re = std::make_unique<RESearch>(&cc);
-		const char *msg = re->Compile(pattern.data(), pattern.length(), true, false);
+		RESearch re(&cc);
+		const char *msg = re.Compile(pattern.data(), pattern.length(), true, false);
 		REQUIRE(nullptr == msg);
 	}
 
 	SECTION("Bug2413") {
 		// Check for https://sourceforge.net/p/scintilla/bugs/2413/
-		std::unique_ptr<RESearch> re = std::make_unique<RESearch>(&cc);
+		RESearch re(&cc);
 		constexpr std::string_view BOW = "\\<";
 		constexpr std::string_view EOW = "\\>";
-		const char *msg = re->Compile(BOW.data(), BOW.length(), true, false);
+		const char *msg = re.Compile(BOW.data(), BOW.length(), true, false);
 		REQUIRE(nullptr == msg);
-		msg = re->Compile(EOW.data(), EOW.length(), true, false);
+		msg = re.Compile(EOW.data(), EOW.length(), true, false);
 		REQUIRE(nullptr == msg);
 	}
 
 	SECTION("Execute") {
-		std::unique_ptr<RESearch> re = std::make_unique<RESearch>(&cc);
-		re->Compile(pattern.data(), pattern.length(), true, false);
-		StringCI sci(sTextSpace);
-		const int x = re->Execute(sci, 0, sci.Length());
+		RESearch re(&cc);
+		re.Compile(pattern.data(), pattern.length(), true, false);
+		const StringCI sci(sTextSpace);
+		const int x = re.Execute(sci, 0, sci.Length());
 		REQUIRE(x == 1);
-		REQUIRE(re->bopat[0] == 1);
-		REQUIRE(re->eopat[0] == sci.Length() - 1);
+		REQUIRE(re.bopat[0] == 1);
+		REQUIRE(re.eopat[0] == sci.Length() - 1);
 	}
 
 	SECTION("Grab") {
-		std::unique_ptr<RESearch> re = std::make_unique<RESearch>(&cc);
-		re->Compile(pattern.data(), pattern.length(), true, false);
-		StringCI sci(sTextSpace);
-		re->Execute(sci, 0, sci.Length());
-		std::string pat = sci.GetCharRange(re->bopat[0], re->eopat[0] - re->bopat[0]);
+		RESearch re(&cc);
+		re.Compile(pattern.data(), pattern.length(), true, false);
+		const StringCI sci(sTextSpace);
+		re.Execute(sci, 0, sci.Length());
+		const std::string pat = sci.GetCharRange(re.bopat[0], re.eopat[0] - re.bopat[0]);
 		REQUIRE(pat == "cintilla");
 	}
 
diff --git a/scintilla/test/unit/testRunStyles.cxx b/scintilla/test/unit/testRunStyles.cxx
index 6c2dffd62..59536ce7b 100644
--- a/scintilla/test/unit/testRunStyles.cxx
+++ b/scintilla/test/unit/testRunStyles.cxx
@@ -37,13 +37,13 @@ TEST_CASE("CompileCopying RunStyles") {
 		RunStyles<int, int> s2;
 
 		// Copy constructor
-		RunStyles<int, int> sa(s);
+		const RunStyles<int, int> sa(s);
 		// Copy assignment fails
 		RunStyles<int, int> sb;
 		sb = s;
 
 		// Move constructor
-		RunStyles<int, int> sc(std::move(s));
+		const RunStyles<int, int> sc(std::move(s));
 		// Move assignment
 		RunStyles<int, int> sd;
 		sd = (std::move(s2));
@@ -72,7 +72,7 @@ TEST_CASE("CompileCopying RunStyles") {
 }
 
 namespace Scintilla::Internal {	// Xcode clang 9.0 doesn't like this when in the unnamed namespace
-	bool operator==(const FillResult<int> &fra, const FillResult<int> &frb) {
+	bool operator==(const FillResult<int> &fra, const FillResult<int> &frb) noexcept {
 		return fra.changed == frb.changed &&
 			fra.position == frb.position &&
 			fra.fillLength == frb.fillLength;
@@ -149,8 +149,8 @@ TEST_CASE("RunStyles") {
 
 	SECTION("FillRange") {
 		rs.InsertSpace(0, 5);
-		int startFill = 1;
-		int lengthFill = 3;
+		const int startFill = 1;
+		const int lengthFill = 3;
 		const auto fr = rs.FillRange(startFill, 99, lengthFill);
 		REQUIRE(FillResult<int>{true, 1, 3} == fr);
 
@@ -169,13 +169,13 @@ TEST_CASE("RunStyles") {
 
 	SECTION("FillRangeAlreadyFilled") {
 		rs.InsertSpace(0, 5);
-		int startFill = 1;
-		int lengthFill = 3;
+		const int startFill = 1;
+		const int lengthFill = 3;
 		const auto fr = rs.FillRange(startFill, 99, lengthFill);
 		REQUIRE(FillResult<int>{true, 1, 3} == fr);
 
-		int startFill2 = 2;
-		int lengthFill2 = 1;
+		const int startFill2 = 2;
+		const int lengthFill2 = 1;
 		// Compiler warnings if 'false' used instead of '0' as expected value:
 		const auto fr2 = rs.FillRange(startFill2, 99, lengthFill2);
 		REQUIRE(FillResult<int>{false, 2, 1} == fr2);
@@ -189,13 +189,13 @@ TEST_CASE("RunStyles") {
 
 	SECTION("FillRangeAlreadyPartFilled") {
 		rs.InsertSpace(0, 5);
-		int startFill = 1;
-		int lengthFill = 2;
+		const int startFill = 1;
+		const int lengthFill = 2;
 		const auto fr = rs.FillRange(startFill, 99, lengthFill);
 		REQUIRE(FillResult<int>{true, 1, 2} == fr);
 
-		int startFill2 = 2;
-		int lengthFill2 = 2;
+		const int startFill2 = 2;
+		const int lengthFill2 = 2;
 		const auto fr2 = rs.FillRange(startFill2, 99, lengthFill2);
 		REQUIRE(FillResult<int>{true, 3, 1} == fr2);
 		REQUIRE(3 == rs.Runs());
@@ -225,8 +225,8 @@ TEST_CASE("RunStyles") {
 
 	SECTION("Find") {
 		rs.InsertSpace(0, 5);
-		int startFill = 1;
-		int lengthFill = 3;
+		const int startFill = 1;
+		const int lengthFill = 3;
 		const auto fr = rs.FillRange(startFill, 99, lengthFill);
 		REQUIRE(FillResult<int>{true, 1, 3} == fr);
 
@@ -261,8 +261,8 @@ TEST_CASE("RunStyles") {
 		REQUIRE(true == rs.AllSame());
 		REQUIRE(false == rs.AllSameAs(88));
 		REQUIRE(true == rs.AllSameAs(0));
-		int startFill = 1;
-		int lengthFill = 3;
+		const int startFill = 1;
+		const int lengthFill = 3;
 		const auto fr = rs.FillRange(startFill, 99, lengthFill);
 		REQUIRE(true == fr.changed);
 		REQUIRE(false == rs.AllSame());
@@ -334,8 +334,8 @@ TEST_CASE("RunStyles") {
 
 	SECTION("DeleteSecond") {
 		rs.InsertSpace(0, 3);
-		int startFill = 1;
-		int lengthFill = 1;
+		const int startFill = 1;
+		const int lengthFill = 1;
 		const auto fr = rs.FillRange(startFill, 99, lengthFill);
 		REQUIRE(true == fr.changed);
 		REQUIRE(3 == rs.Length());
@@ -347,8 +347,8 @@ TEST_CASE("RunStyles") {
 
 	SECTION("DeleteEndRun") {
 		rs.InsertSpace(0, 2);
-		int startFill = 1;
-		int lengthFill = 1;
+		const int startFill = 1;
+		const int lengthFill = 1;
 		const auto fr = rs.FillRange(startFill, 99, lengthFill);
 		REQUIRE(true == fr.changed);
 		REQUIRE(2 == rs.Length());
@@ -369,8 +369,8 @@ TEST_CASE("RunStyles") {
 
 	SECTION("OutsideBounds") {
 		rs.InsertSpace(0, 1);
-		int startFill = 1;
-		int lengthFill = 1;
+		const int startFill = 1;
+		const int lengthFill = 1;
 		rs.FillRange(startFill, 99, lengthFill);
 		REQUIRE(1 == rs.Length());
 		REQUIRE(1 == rs.Runs());
diff --git a/scintilla/test/unit/testSparseVector.cxx b/scintilla/test/unit/testSparseVector.cxx
index 3a784d4c2..157acfc2d 100644
--- a/scintilla/test/unit/testSparseVector.cxx
+++ b/scintilla/test/unit/testSparseVector.cxx
@@ -39,13 +39,13 @@ TEST_CASE("CompileCopying SparseVector") {
 		SparseVector<int> s2;
 
 		// Copy constructor
-		SparseVector<int> sa(s);
+		const SparseVector<int> sa(s);
 		// Copy assignment
 		SparseVector<int> sb;
 		sb = s;
 
 		// Move constructor
-		SparseVector<int> sc(std::move(s));
+		const SparseVector<int> sc(std::move(s));
 		// Move assignment
 		SparseVector<int> sd;
 		sd = (std::move(s2));
@@ -64,17 +64,20 @@ TEST_CASE("CompileCopying SparseVector") {
 #endif
 
 		// Move constructor
-		SparseVector<UniqueInt> sc(std::move(s));
+		const SparseVector<UniqueInt> sc(std::move(s));
 		// Move assignment
+		SparseVector<UniqueInt> s2;
 		SparseVector<UniqueInt> sd;
-		sd = (std::move(s));
+		sd = (std::move(s2));
 	}
 
 }
 
+namespace {
+
 // Helper to produce a string representation of a SparseVector<const char *>
 // to simplify checks.
-static std::string Representation(const SparseVector<UniqueString> &st) {
+std::string Representation(const SparseVector<UniqueString> &st) {
 	std::string ret;
 	for (int i = 0;i <= st.Length();i++) {
 		const char *value = st.ValueAt(i).get();
@@ -86,6 +89,8 @@ static std::string Representation(const SparseVector<UniqueString> &st) {
 	return ret;
 }
 
+}
+
 TEST_CASE("SparseVector") {
 
 	SparseVector<UniqueString> st;
@@ -472,7 +477,7 @@ TEST_CASE("SparseTextString") {
 	SECTION("SetAndMoveString") {
 		st.InsertSpace(0, 2);
 		REQUIRE(2u == st.Length());
-		std::string s24("24");
+		const std::string s24("24");
 		st.SetValueAt(0, s24);
 		REQUIRE("24" == s24);	// Not moved from
 		REQUIRE("" == st.ValueAt(-1));
@@ -480,7 +485,8 @@ TEST_CASE("SparseTextString") {
 		REQUIRE("" == st.ValueAt(1));
 		std::string s25("25");
 		st.SetValueAt(1, std::move(s25));
-		REQUIRE("" == s25);	// moved from
+		// Deliberate check of moved from: provokes warning from Visual C++ code analysis
+		REQUIRE("" == s25);
 		REQUIRE("25" == st.ValueAt(1));
 	}
 
diff --git a/scintilla/test/unit/testSplitVector.cxx b/scintilla/test/unit/testSplitVector.cxx
index 543c40b3f..cadd44b97 100644
--- a/scintilla/test/unit/testSplitVector.cxx
+++ b/scintilla/test/unit/testSplitVector.cxx
@@ -37,13 +37,13 @@ TEST_CASE("CompileCopying SplitVector") {
 		SplitVector<int> s2;
 
 		// Copy constructor fails
-		SplitVector<int> sa(s);
+		const SplitVector<int> sa(s);
 		// Copy assignment fails
 		SplitVector<int> sb;
 		sb = s;
 
 		// Move constructor fails
-		SplitVector<int> sc(std::move(s));
+		const SplitVector<int> sc(std::move(s));
 		// Move assignment fails
 		SplitVector<int> sd;
 		sd = (std::move(s2));
@@ -62,7 +62,7 @@ TEST_CASE("CompileCopying SplitVector") {
 #endif
 
 		// Move constructor fails
-		SplitVector<UniqueInt> sc(std::move(s));
+		const SplitVector<UniqueInt> sc(std::move(s));
 		// Move assignment fails
 		SplitVector<UniqueInt> sd;
 		sd = (std::move(s));
@@ -72,7 +72,7 @@ TEST_CASE("CompileCopying SplitVector") {
 
 struct StringSetHolder {
 	SplitVector<std::string> sa;
-	bool Check() const noexcept {
+	[[nodiscard]] bool Check() const noexcept {
 		for (int i = 0; i < sa.Length(); i++) {
 			if (sa[i].empty()) {
 				return false;
@@ -374,7 +374,7 @@ TEST_CASE("SplitVector") {
 	SECTION("DeleteBackAndForth") {
 		sv.InsertValue(0, 10, 87);
 		for (int i=0; i<10; i+=2) {
-			int len = 10 - i;
+			const int len = 10 - i;
 			REQUIRE(len == sv.Length());
 			for (int j=0; j<sv.Length(); j++) {
 				REQUIRE(87 == sv.ValueAt(j));
diff --git a/scintilla/test/unit/testUniConversion.cxx b/scintilla/test/unit/testUniConversion.cxx
index 9c313390a..0327db7e1 100644
--- a/scintilla/test/unit/testUniConversion.cxx
+++ b/scintilla/test/unit/testUniConversion.cxx
@@ -28,53 +28,53 @@ TEST_CASE("UTF16Length") {
 	SECTION("UTF16Length ASCII") {
 		// Latin Small Letter A
 		const char *s = "a";
-		size_t len = UTF16Length(s);
+		const size_t len = UTF16Length(s);
 		REQUIRE(len == 1U);
 	}
 
 	SECTION("UTF16Length Example1") {
 		// Dollar Sign
 		const char *s = "\x24";
-		size_t len = UTF16Length(s);
+		const size_t len = UTF16Length(s);
 		REQUIRE(len == 1U);
 	}
 
 	SECTION("UTF16Length Example2") {
 		// Cent Sign
 		const char *s = "\xC2\xA2";
-		size_t len = UTF16Length(s);
+		const size_t len = UTF16Length(s);
 		REQUIRE(len == 1U);
 	}
 
 	SECTION("UTF16Length Example3") {
 		// Euro Sign
 		const char *s = "\xE2\x82\xAC";
-		size_t len = UTF16Length(s);
+		const size_t len = UTF16Length(s);
 		REQUIRE(len == 1U);
 	}
 
 	SECTION("UTF16Length Example4") {
 		// Gothic Letter Hwair
 		const char *s = "\xF0\x90\x8D\x88";
-		size_t len = UTF16Length(s);
+		const size_t len = UTF16Length(s);
 		REQUIRE(len == 2U);
 	}
 
 	SECTION("UTF16Length Invalid Trail byte in lead position") {
 		const char *s = "a\xB5yz";
-		size_t len = UTF16Length(s);
+		const size_t len = UTF16Length(s);
 		REQUIRE(len == 4U);
 	}
 
 	SECTION("UTF16Length Invalid Lead byte at end") {
 		const char *s = "a\xC2";
-		size_t len = UTF16Length(s);
+		const size_t len = UTF16Length(s);
 		REQUIRE(len == 2U);
 	}
 
 	SECTION("UTF16Length Invalid Lead byte implies 3 trails but only 2") {
 		const char *s = "a\xF1yz";
-		size_t len = UTF16Length(s);
+		const size_t len = UTF16Length(s);
 		REQUIRE(len == 2U);
 	}
 }
@@ -113,7 +113,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF16FromUTF8 ASCII") {
 		const char s[] = {'a', 0};
 		wchar_t tbuf[1] = {0};
-		size_t tlen = UTF16FromUTF8(s, tbuf, 1);
+		const size_t tlen = UTF16FromUTF8(s, tbuf, 1);
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == 'a');
 	}
@@ -121,7 +121,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF16FromUTF8 Example1") {
 		const char s[] = {'\x24', 0};
 		wchar_t tbuf[1] = {0};
-		size_t tlen = UTF16FromUTF8(s, tbuf, 1);
+		const size_t tlen = UTF16FromUTF8(s, tbuf, 1);
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == 0x24);
 	}
@@ -129,7 +129,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF16FromUTF8 Example2") {
 		const char s[] = {'\xC2', '\xA2', 0};
 		wchar_t tbuf[1] = {0};
-		size_t tlen = UTF16FromUTF8(s, tbuf, 1);
+		const size_t tlen = UTF16FromUTF8(s, tbuf, 1);
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == 0xA2);
 	}
@@ -137,7 +137,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF16FromUTF8 Example3") {
 		const char s[] = {'\xE2', '\x82', '\xAC', 0};
 		wchar_t tbuf[1] = {0};
-		size_t tlen = UTF16FromUTF8(s, tbuf, 1);;
+		const size_t tlen = UTF16FromUTF8(s, tbuf, 1);;
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == 0x20AC);
 	}
@@ -145,7 +145,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF16FromUTF8 Example4") {
 		const char s[] = {'\xF0', '\x90', '\x8D', '\x88', 0};
 		wchar_t tbuf[2] = {0, 0};
-		size_t tlen = UTF16FromUTF8(s, tbuf, 2);
+		const size_t tlen = UTF16FromUTF8(s, tbuf, 2);
 		REQUIRE(tlen == 2U);
 		REQUIRE(tbuf[0] == 0xD800);
 		REQUIRE(tbuf[1] == 0xDF48);
@@ -154,7 +154,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF16FromUTF8 Invalid Trail byte in lead position") {
 		const char s[] = "a\xB5yz";
 		wchar_t tbuf[4] = {};
-		size_t tlen = UTF16FromUTF8(s, tbuf, 4);
+		const size_t tlen = UTF16FromUTF8(s, tbuf, 4);
 		REQUIRE(tlen == 4U);
 		REQUIRE(tbuf[0] == 'a');
 		REQUIRE(tbuf[1] == 0xB5);
@@ -165,7 +165,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF16FromUTF8 Invalid Lead byte at end") {
 		const char s[] = "a\xC2";
 		wchar_t tbuf[2] = {};
-		size_t tlen = UTF16FromUTF8(s, tbuf, 2);
+		const size_t tlen = UTF16FromUTF8(s, tbuf, 2);
 		REQUIRE(tlen == 2U);
 		REQUIRE(tbuf[0] == 'a');
 		REQUIRE(tbuf[1] == 0xC2);
@@ -174,7 +174,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF16FromUTF8 Invalid Lead byte implies 3 trails but only 2") {
 		const char *s = "a\xF1yz";
 		wchar_t tbuf[4] = {};
-		size_t tlen = UTF16FromUTF8(s, tbuf, 4);
+		const size_t tlen = UTF16FromUTF8(s, tbuf, 4);
 		REQUIRE(tlen == 2U);
 		REQUIRE(tbuf[0] == 'a');
 		REQUIRE(tbuf[1] == 0xF1);
@@ -185,7 +185,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF32FromUTF8 ASCII") {
 		const char s[] = {'a', 0};
 		unsigned int tbuf[1] = {0};
-		size_t tlen = UTF32FromUTF8(s, tbuf, 1);
+		const size_t tlen = UTF32FromUTF8(s, tbuf, 1);
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == static_cast<unsigned int>('a'));
 	}
@@ -193,7 +193,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF32FromUTF8 Example1") {
 		const char s[] = {'\x24', 0};
 		unsigned int tbuf[1] = {0};
-		size_t tlen = UTF32FromUTF8(s, tbuf, 1);
+		const size_t tlen = UTF32FromUTF8(s, tbuf, 1);
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == 0x24);
 	}
@@ -201,7 +201,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF32FromUTF8 Example2") {
 		const char s[] = {'\xC2', '\xA2', 0};
 		unsigned int tbuf[1] = {0};
-		size_t tlen = UTF32FromUTF8(s, tbuf, 1);
+		const size_t tlen = UTF32FromUTF8(s, tbuf, 1);
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == 0xA2);
 	}
@@ -209,7 +209,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF32FromUTF8 Example3") {
 		const char s[] = {'\xE2', '\x82', '\xAC', 0};
 		unsigned int tbuf[1] = {0};
-		size_t tlen = UTF32FromUTF8(s, tbuf, 1);
+		const size_t tlen = UTF32FromUTF8(s, tbuf, 1);
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == 0x20AC);
 	}
@@ -217,7 +217,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF32FromUTF8 Example4") {
 		const char s[] = {'\xF0', '\x90', '\x8D', '\x88', 0};
 		unsigned int tbuf[1] = {0};
-		size_t tlen = UTF32FromUTF8(s, tbuf, 1);
+		const size_t tlen = UTF32FromUTF8(s, tbuf, 1);
 		REQUIRE(tlen == 1U);
 		REQUIRE(tbuf[0] == 0x10348);
 	}
@@ -225,7 +225,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF32FromUTF8 Invalid Trail byte in lead position") {
 		const char s[] = "a\xB5yz";
 		unsigned int tbuf[4] = {};
-		size_t tlen = UTF32FromUTF8(s, tbuf, 4);
+		const size_t tlen = UTF32FromUTF8(s, tbuf, 4);
 		REQUIRE(tlen == 4U);
 		REQUIRE(tbuf[0] == static_cast<unsigned int>('a'));
 		REQUIRE(tbuf[1] == 0xB5);
@@ -236,7 +236,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF32FromUTF8 Invalid Lead byte at end") {
 		const char s[] = "a\xC2";
 		unsigned int tbuf[2] = {};
-		size_t tlen = UTF32FromUTF8(s, tbuf, 2);
+		const size_t tlen = UTF32FromUTF8(s, tbuf, 2);
 		REQUIRE(tlen == 2U);
 		REQUIRE(tbuf[0] == static_cast<unsigned int>('a'));
 		REQUIRE(tbuf[1] == 0xC2);
@@ -245,7 +245,7 @@ TEST_CASE("UniConversion") {
 	SECTION("UTF32FromUTF8 Invalid Lead byte implies 3 trails but only 2") {
 		const char *s = "a\xF1yz";
 		unsigned int tbuf[4] = {};
-		size_t tlen = UTF32FromUTF8(s, tbuf, 4);
+		const size_t tlen = UTF32FromUTF8(s, tbuf, 4);
 		REQUIRE(tlen == 2U);
 		REQUIRE(tbuf[0] == static_cast<unsigned int>('a'));
 		REQUIRE(tbuf[1] == 0xF1);
diff --git a/scintilla/version.txt b/scintilla/version.txt
index c536da932..32203d46c 100644
--- a/scintilla/version.txt
+++ b/scintilla/version.txt
@@ -1 +1 @@
-541
+542
diff --git a/scintilla/win32/PlatWin.cxx b/scintilla/win32/PlatWin.cxx
index 8d84292ce..c660ae97a 100644
--- a/scintilla/win32/PlatWin.cxx
+++ b/scintilla/win32/PlatWin.cxx
@@ -98,8 +98,8 @@ void LoadD2DOnce() noexcept {
 	hDLLD2D = ::LoadLibraryEx(TEXT("D2D1.DLL"), 0, loadLibraryFlags);
 	D2D1CFSig fnD2DCF = DLLFunction<D2D1CFSig>(hDLLD2D, "D2D1CreateFactory");
 	if (fnD2DCF) {
-		// A single threaded factory as Scintilla always draw on the GUI thread
-		fnD2DCF(D2D1_FACTORY_TYPE_SINGLE_THREADED,
+		// A multi threaded factory in case Scintilla is used with multiple GUI threads
+		fnD2DCF(D2D1_FACTORY_TYPE_MULTI_THREADED,
 			__uuidof(ID2D1Factory),
 			nullptr,
 			reinterpret_cast<IUnknown**>(&pD2DFactory));
@@ -3358,7 +3358,7 @@ void ListBoxX::SetList(const char *list, char separator, char typesep) {
 	Clear();
 	const size_t size = strlen(list);
 	char *words = lti.SetWords(list);
-	char *startword = words;
+	const char *startword = words;
 	char *numword = nullptr;
 	for (size_t i=0; i < size; i++) {
 		if (words[i] == separator) {
diff --git a/scintilla/win32/ScintRes.rc b/scintilla/win32/ScintRes.rc
index 1b5a4d500..08a73d9aa 100644
--- a/scintilla/win32/ScintRes.rc
+++ b/scintilla/win32/ScintRes.rc
@@ -4,8 +4,8 @@
 
 #include <windows.h>
 
-#define VERSION_SCINTILLA "5.4.1"
-#define VERSION_WORDS 5, 4, 1, 0
+#define VERSION_SCINTILLA "5.4.2"
+#define VERSION_WORDS 5, 4, 2, 0
 
 VS_VERSION_INFO VERSIONINFO
 FILEVERSION	VERSION_WORDS
diff --git a/scintilla/win32/ScintillaWin.cxx b/scintilla/win32/ScintillaWin.cxx
index ca2131434..8a808ac95 100644
--- a/scintilla/win32/ScintillaWin.cxx
+++ b/scintilla/win32/ScintillaWin.cxx
@@ -166,7 +166,11 @@ void SetWindowID(HWND hWnd, int identifier) noexcept {
 	::SetWindowLongPtr(hWnd, GWLP_ID, identifier);
 }
 
-Point PointFromLParam(sptr_t lpoint) noexcept {
+constexpr POINT POINTFromLParam(sptr_t lParam) noexcept {
+	return { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };
+};
+
+constexpr Point PointFromLParam(sptr_t lpoint) noexcept {
 	return Point::FromInts(GET_X_LPARAM(lpoint), GET_Y_LPARAM(lpoint));
 }
 
@@ -352,6 +356,13 @@ struct HorizontalScrollRange {
 	int documentWidth;
 };
 
+CLIPFORMAT RegisterClipboardType(LPCWSTR lpszFormat) noexcept {
+	// Registered clipboard format values are 0xC000 through 0xFFFF.
+	// RegisterClipboardFormatW returns 32-bit unsigned and CLIPFORMAT is 16-bit
+	// unsigned so choose the low 16-bits with &.
+	return ::RegisterClipboardFormatW(lpszFormat) & 0xFFFF;
+}
+
 }
 
 namespace Scintilla::Internal {
@@ -605,16 +616,12 @@ ScintillaWin::ScintillaWin(HWND hwnd) {
 
 	// There does not seem to be a real standard for indicating that the clipboard
 	// contains a rectangular selection, so copy Developer Studio and Borland Delphi.
-	cfColumnSelect = static_cast<CLIPFORMAT>(
-		::RegisterClipboardFormat(TEXT("MSDEVColumnSelect")));
-	cfBorlandIDEBlockType = static_cast<CLIPFORMAT>(
-		::RegisterClipboardFormat(TEXT("Borland IDE Block Type")));
+	cfColumnSelect = RegisterClipboardType(L"MSDEVColumnSelect");
+	cfBorlandIDEBlockType = RegisterClipboardType(L"Borland IDE Block Type");
 
 	// Likewise for line-copy (copies a full line when no text is selected)
-	cfLineSelect = static_cast<CLIPFORMAT>(
-		::RegisterClipboardFormat(TEXT("MSDEVLineSelect")));
-	cfVSLineTag = static_cast<CLIPFORMAT>(
-		::RegisterClipboardFormat(TEXT("VisualStudioEditorOperationsLineCutCopyClipboardTag")));
+	cfLineSelect = RegisterClipboardType(L"MSDEVLineSelect");
+	cfVSLineTag = RegisterClipboardType(L"VisualStudioEditorOperationsLineCutCopyClipboardTag");
 	hrOle = E_FAIL;
 
 	wMain = hwnd;
@@ -1551,19 +1558,21 @@ Window::Cursor ScintillaWin::ContextCursor(Point pt) {
 }
 
 sptr_t ScintillaWin::ShowContextMenu(unsigned int iMessage, uptr_t wParam, sptr_t lParam) {
-	Point pt = PointFromLParam(lParam);
-	POINT rpt = POINTFromPoint(pt);
-	::ScreenToClient(MainHWND(), &rpt);
-	const Point ptClient = PointFromPOINT(rpt);
+	Point ptScreen = PointFromLParam(lParam);
+	Point ptClient;
+	POINT point = POINTFromLParam(lParam);
+	if ((point.x == -1) && (point.y == -1)) {
+		// Caused by keyboard so display menu near caret
+		ptClient = PointMainCaret();
+		point = POINTFromPoint(ptClient);
+		::ClientToScreen(MainHWND(), &point);
+		ptScreen = PointFromPOINT(point);
+	} else {
+		::ScreenToClient(MainHWND(), &point);
+		ptClient = PointFromPOINT(point);
+	}
 	if (ShouldDisplayPopup(ptClient)) {
-		if ((pt.x == -1) && (pt.y == -1)) {
-			// Caused by keyboard so display menu near caret
-			pt = PointMainCaret();
-			POINT spt = POINTFromPoint(pt);
-			::ClientToScreen(MainHWND(), &spt);
-			pt = PointFromPOINT(spt);
-		}
-		ContextMenu(pt);
+		ContextMenu(ptScreen);
 		return 0;
 	}
 	return ::DefWindowProc(MainHWND(), iMessage, wParam, lParam);
@@ -1652,7 +1661,7 @@ sptr_t ScintillaWin::MouseMessage(unsigned int iMessage, uptr_t wParam, sptr_t l
 			// handle the message but pass it on.
 			RECT rc;
 			GetWindowRect(MainHWND(), &rc);
-			const POINT pt = { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };
+			const POINT pt = POINTFromLParam(lParam);
 			if (!PtInRect(&rc, pt))
 				return ::DefWindowProc(MainHWND(), iMessage, wParam, lParam);
 		}
@@ -3754,8 +3763,8 @@ LRESULT PASCAL ScintillaWin::CTWndProc(
 				::EndPaint(hWnd, &ps);
 				return 0;
 			} else if ((iMessage == WM_NCLBUTTONDOWN) || (iMessage == WM_NCLBUTTONDBLCLK)) {
-				POINT pt = { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };
-				ScreenToClient(hWnd, &pt);
+				POINT pt = POINTFromLParam(lParam);
+				::ScreenToClient(hWnd, &pt);
 				sciThis->ct.MouseClick(PointFromPOINT(pt));
 				sciThis->CallTipClick();
 				return 0;
diff --git a/scintilla/win32/deps.mak b/scintilla/win32/deps.mak
index 1b9c89011..ff58fae3c 100644
--- a/scintilla/win32/deps.mak
+++ b/scintilla/win32/deps.mak
@@ -101,6 +101,7 @@ $(DIR_O)/CellBuffer.o: \
 	../src/SparseVector.h \
 	../src/ChangeHistory.h \
 	../src/CellBuffer.h \
+	../src/UndoHistory.h \
 	../src/UniConversion.h
 $(DIR_O)/ChangeHistory.o: \
 	../src/ChangeHistory.cxx \
@@ -437,6 +438,18 @@ $(DIR_O)/Style.o: \
 	../src/Geometry.h \
 	../src/Platform.h \
 	../src/Style.h
+$(DIR_O)/UndoHistory.o: \
+	../src/UndoHistory.cxx \
+	../include/ScintillaTypes.h \
+	../src/Debugging.h \
+	../src/Position.h \
+	../src/SplitVector.h \
+	../src/Partitioning.h \
+	../src/RunStyles.h \
+	../src/SparseVector.h \
+	../src/ChangeHistory.h \
+	../src/CellBuffer.h \
+	../src/UndoHistory.h
 $(DIR_O)/UniConversion.o: \
 	../src/UniConversion.cxx \
 	../src/UniConversion.h
diff --git a/scintilla/win32/makefile b/scintilla/win32/makefile
index 7f6c4bea2..ab6926ee4 100644
--- a/scintilla/win32/makefile
+++ b/scintilla/win32/makefile
@@ -108,6 +108,7 @@ SRC_OBJS = \
 	$(DIR_O)/RunStyles.o \
 	$(DIR_O)/Selection.o \
 	$(DIR_O)/Style.o \
+	$(DIR_O)/UndoHistory.o \
 	$(DIR_O)/UniConversion.o \
 	$(DIR_O)/UniqueString.o \
 	$(DIR_O)/ViewStyle.o \
diff --git a/scintilla/win32/nmdeps.mak b/scintilla/win32/nmdeps.mak
index 62ada451c..961aba5ee 100644
--- a/scintilla/win32/nmdeps.mak
+++ b/scintilla/win32/nmdeps.mak
@@ -101,6 +101,7 @@ $(DIR_O)/CellBuffer.obj: \
 	../src/SparseVector.h \
 	../src/ChangeHistory.h \
 	../src/CellBuffer.h \
+	../src/UndoHistory.h \
 	../src/UniConversion.h
 $(DIR_O)/ChangeHistory.obj: \
 	../src/ChangeHistory.cxx \
@@ -437,6 +438,18 @@ $(DIR_O)/Style.obj: \
 	../src/Geometry.h \
 	../src/Platform.h \
 	../src/Style.h
+$(DIR_O)/UndoHistory.obj: \
+	../src/UndoHistory.cxx \
+	../include/ScintillaTypes.h \
+	../src/Debugging.h \
+	../src/Position.h \
+	../src/SplitVector.h \
+	../src/Partitioning.h \
+	../src/RunStyles.h \
+	../src/SparseVector.h \
+	../src/ChangeHistory.h \
+	../src/CellBuffer.h \
+	../src/UndoHistory.h
 $(DIR_O)/UniConversion.obj: \
 	../src/UniConversion.cxx \
 	../src/UniConversion.h
diff --git a/scintilla/win32/scintilla.mak b/scintilla/win32/scintilla.mak
index 05581bad8..f0ed869c0 100644
--- a/scintilla/win32/scintilla.mak
+++ b/scintilla/win32/scintilla.mak
@@ -104,6 +104,7 @@ SRC_OBJS=\
 	$(DIR_O)\RunStyles.obj \
 	$(DIR_O)\Selection.obj \
 	$(DIR_O)\Style.obj \
+	$(DIR_O)\UndoHistory.obj \
 	$(DIR_O)\UniConversion.obj \
 	$(DIR_O)\UniqueString.obj \
 	$(DIR_O)\ViewStyle.obj \