Fix #43 alternate shortcut for copy (Ctrl+Ins) not working if Options.AllowToggleOverstrikeMode is enabled.

Based on @nippur72's fix in #44.

ICSharpCode.AvalonEdit/AvalonEditCommands.cs

@@ -26,6 +26,16 @@ namespace ICSharpCode.AvalonEdit
 	/// </summary>
 	public static class AvalonEditCommands
 	{
+		/// <summary>
+		/// Toggles Overstrike mode
+		/// The default shortcut is Ins.
+		/// </summary>
+		public static readonly RoutedCommand ToggleOverstrike = new RoutedCommand(
+			"ToggleOverstrike", typeof(TextEditor),
+			new InputGestureCollection {
+				new KeyGesture(Key.Insert)
+			});
+
 		/// <summary>
 		/// Deletes the current line.
 		/// The default shortcut is Ctrl+D.

ICSharpCode.AvalonEdit/Editing/EditingCommandHandler.cs

@@ -78,6 +78,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 			CommandBindings.Add(new CommandBinding(ApplicationCommands.Cut, OnCut, CanCutOrCopy));
 			CommandBindings.Add(new CommandBinding(ApplicationCommands.Paste, OnPaste, CanPaste));
 			
+			CommandBindings.Add(new CommandBinding(AvalonEditCommands.ToggleOverstrike, OnToggleOverstrike));
 			CommandBindings.Add(new CommandBinding(AvalonEditCommands.DeleteLine, OnDeleteLine));
 			
 			CommandBindings.Add(new CommandBinding(AvalonEditCommands.RemoveLeadingWhitespace, OnRemoveLeadingWhitespace));
@@ -484,6 +485,15 @@ namespace ICSharpCode.AvalonEdit.Editing
 		}
 		#endregion
 		
+		#region Toggle Overstrike
+		static void OnToggleOverstrike(object target, ExecutedRoutedEventArgs args)
+		{
+			TextArea textArea = GetTextArea(target);
+			if (textArea != null && textArea.Options.AllowToggleOverstrikeMode) 
+				textArea.OverstrikeMode = !textArea.OverstrikeMode;
+		}
+		#endregion
+		
 		#region DeleteLine
 		static void OnDeleteLine(object target, ExecutedRoutedEventArgs args)
 		{

ICSharpCode.AvalonEdit/Editing/TextArea.cs

@@ -971,13 +971,6 @@ namespace ICSharpCode.AvalonEdit.Editing
 		protected override void OnPreviewKeyDown(KeyEventArgs e)
 		{
 			base.OnPreviewKeyDown(e);
-			
-			if (!e.Handled && e.Key == Key.Insert && this.Options.AllowToggleOverstrikeMode) {
-				this.OverstrikeMode = !this.OverstrikeMode;
-				e.Handled = true;
-				return;
-			}
-			
 			foreach (TextAreaStackedInputHandler h in stackedInputHandlers) {
 				if (e.Handled)
 					break;