protected override void Cleanup()
{
editModeWorker.Cleanup();
//CommandManager.RemovePreviewCanExecuteHandler(TargetElement, PreviewCanExecuteCommand);
TargetElement.RemoveHandler(FrameworkElement.PreviewKeyDownEvent, new RoutedEventHandler(TargetElement_PreviewKeyDown));
//TargetElement.PreviewKeyDown -= TargetElement_PreviewKeyDown;
TargetElement.PreviewMouseDown -= TargetElement_PreviewMouseDown;
SetEditingExtender(TargetElement, null);
}