Fix that only one default dashboard could be removed

fixes #11078

application/views/scripts/dashboard/settings.phtml

@@ -18,6 +18,7 @@
         </thead>
         <tbody>
             <?php foreach ($this->dashboard->getPanes() as $pane): ?>
+                <?php if ($pane->getDisabled()) continue; ?>
                 <tr style="background-color: #f1f1f1;">
                     <th colspan="2" style="text-align: left; padding: 0.5em;">
                         <?= $this->escape($pane->getName()) ?>
@@ -43,7 +44,7 @@
                     </tr>
                 <?php else: ?>
                     <?php foreach ($dashlets as $dashlet): ?>
-                    <?php if ($dashlet->getDisabled() === true) continue; ?>
+                    <?php if ($dashlet->getDisabled()) continue; ?>
                         <tr>
                             <td>
                                 <?= $this->qlink(

library/Icinga/Web/Widget/Dashboard.php

@@ -201,12 +201,6 @@ class Dashboard extends AbstractWidget
     {
         /** @var $pane Pane  */
         foreach ($panes as $pane) {
-            if ($pane->getDisabled()) {
-                if ($this->hasPane($pane->getTitle()) === true) {
-                    $this->removePane($pane->getTitle());
-                }
-                continue;
-            }
             if ($this->hasPane($pane->getTitle()) === true) {
                 /** @var $current Pane */
                 $current = $this->panes[$pane->getName()];
@@ -231,6 +225,9 @@ class Dashboard extends AbstractWidget
             $this->tabs = new Tabs();
 
             foreach ($this->panes as $key => $pane) {
+                if ($pane->getDisabled()) {
+                    continue;
+                }
                 $this->tabs->add(
                     $key,
                     array(

library/Icinga/Web/Widget/Dashboard/Pane.php

@@ -40,7 +40,7 @@ class Pane extends UserWidget
      *
      * @var bool
      */
-    private $disabled;
+    private $disabled = false;
 
     /**
      * Create a new pane