[FZE] Fix crash when double clicking edit layout (#12609)

src/modules/fancyzones/editor/FancyZonesEditor/MainWindow.xaml.cs

@@ -26,6 +26,7 @@ namespace FancyZonesEditor
         private LayoutModel _backup;
 
         private ContentDialog _openedDialog;
+        private bool _openingDialog = false; // Is the dialog being opened.
 
         public int WrapPanelItemSize { get; set; } = DefaultWrapPanelItemSize;
 
@@ -246,6 +247,12 @@ namespace FancyZonesEditor
         }
 
         private async void EditLayout_Click(object sender, RoutedEventArgs e)
+        {
+            // Avoid trying to open the same dialog twice.
+            if (!_openingDialog)
+            {
+                _openingDialog = true;
+                try
                 {
                     var dataContext = ((FrameworkElement)sender).DataContext;
                     Select((LayoutModel)dataContext);
@@ -261,6 +268,13 @@ namespace FancyZonesEditor
 
                     await EditLayoutDialog.ShowAsync();
                 }
+                catch
+                {
+                    _openingDialog = false;
+                    throw;
+                }
+            }
+        }
 
         private void EditZones_Click(object sender, RoutedEventArgs e)
         {
@@ -411,6 +425,7 @@ namespace FancyZonesEditor
 
         private void Dialog_Closed(ContentDialog sender, ContentDialogClosedEventArgs args)
         {
+            _openingDialog = false;
             _openedDialog = null;
         }