private void CompositionTarget_Rendering(object sender, object e)
{
CompositionTarget.Rendering -= new EventHandler<object>(this.CompositionTarget_Rendering);
Action a = delegate
{
base.OnLayerChanged();
this.isInvalidated = false;
};
DispatchedHandler handler = new DispatchedHandler(a);
base.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, handler);
}