Fix visual glitchy on clicking on tab due to Document Peeker.

Closes #3367

PowerEditor/src/WinControls/TabBar/TabBar.cpp

@@ -597,28 +597,9 @@ LRESULT TabBarPlus::runProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lPara
 				return TRUE;
 
             if (_doDragNDrop)
-            {
-				// ::DragDetect does not work with TCS_BUTTONS
-				if (::GetWindowLongPtr(_hSelf, GWL_STYLE) & TCS_BUTTONS)
             {
 				_mightBeDragging = true;
             }
-				else
-				{
-					_nSrcTab = _nTabDragged = currentTabOn;
-
-					POINT point;
-					point.x = LOWORD(lParam);
-					point.y = HIWORD(lParam);
-					::ClientToScreen(hwnd, &point);
-					if(::DragDetect(hwnd, point))
-					{
-						// Yes, we're beginning to drag, so capture the mouse...
-						_isDragging = true;
-						::SetCapture(hwnd);
-					}
-				}
-            }
 
 			notify(NM_CLICK, currentTabOn);
 
@@ -658,6 +639,12 @@ LRESULT TabBarPlus::runProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lPara
 
 					_nSrcTab = _nTabDragged = tabFocused;
 					_isDragging = true;
+					
+					// ::SetCapture is required for normal non-TLS_BUTTONS.
+					if (!(::GetWindowLongPtr(_hSelf, GWL_STYLE) & TCS_BUTTONS))
+					{
+						::SetCapture(hwnd);
+					}
 				}
 			}