private void OnAdornerPropertyChanged(object sender, AdornerPropertyChangedEventArgs eventArgs)
 {
     if (!this.AdornerSet.ElementSet.IsAttached)
     {
         this.Unhook();
     }
     else
     {
         this.HandleAdornerLayerEvent(eventArgs);
     }
 }
 protected abstract void HandleAdornerLayerEvent(AdornerPropertyChangedEventArgs eventArgs);