protected override void Setup()
{
SetEditingExtender(TargetElement, this);
UpdateEditMode();
TargetElement.AddHandler(FrameworkElement.PreviewKeyDownEvent, new RoutedEventHandler(TargetElement_PreviewKeyDown), true);
//TargetElement.PreviewKeyDown += TargetElement_PreviewKeyDown;
TargetElement.PreviewMouseDown += TargetElement_PreviewMouseDown;
}