AnimatePaneBox.cs

 public static void AnimatePaneBox(this IMain form, ContentControl destination, UIElementCollection source, Action<FrameworkElement, IEnumerable<WorkItem>> action, FrameworkElement parent, IEnumerable<WorkItem> itemsToDelselect)
{
	// Create a NameScope for this page so that
	// Storyboards can be used.
	NameScope.SetNameScope((DependencyObject)form, new NameScope());

	Canvas containerCanvas = new Canvas();

	int curInteration = 0;

	foreach (FrameworkElement element in source)
	{
		curInteration++;
		string iterationName = "iter" + curInteration.ToString();

		GeneralTransform tranform;

		try
		{
			// Try to get a transform object.  It may not be possible. 
			// (ie if the source or dest is not docked then it will fail and we cannot animate.
			tranform = element.TransformToVisual(destination);
		}
		catch (InvalidOperationException)
		{
			return;
		}


		Point rootPoint = tranform.Transform(new Point(0, 0));

		Rect sourceRelativeRect = new Rect(rootPoint.X - (destination.ActualWidth / 2),
			rootPoint.Y - (destination.ActualHeight / 2), element.ActualWidth, element.ActualHeight);

		RectangleGeometry myRectangleGeometry = new RectangleGeometry { Rect = new Rect(0, 0, 0, 0) };

		// Assign the geometry a name so that
		// it can be targeted by a Storyboard.
		form.WindowRegisterName(iterationName, myRectangleGeometry);

		Path myPath = new Path
		{
			Fill = ((Canvas)element).Background,
			StrokeThickness = 1,
			Stroke = Brushes.Black,
			Data = myRectangleGeometry
		};


		RectAnimation myRectAnimation = new RectAnimation
		{
			Duration = TimeSpan.FromSeconds(1),
			FillBehavior = FillBehavior.Stop,
			AccelerationRatio = 1,
			// Set the From and To properties of the animation.
			From = sourceRelativeRect,
			To = new Rect(0, 0, 0, 0)
		};

		// Set the animation to target the Rect property
		// of the object named "MyAnimatedRectangleGeometry."
		Storyboard.SetTargetName(myRectAnimation, iterationName);
		Storyboard.SetTargetProperty(myRectAnimation, new PropertyPath(RectangleGeometry.RectProperty));

		// Create a storyboard to apply the animation.
		Storyboard ellipseStoryboard = new Storyboard();
		ellipseStoryboard.Children.Add(myRectAnimation);
		containerCanvas.Children.Add(myPath);

		// Start the storyboard when the Path loads.
		myPath.Loaded += ((sender, e) => ellipseStoryboard.Begin((FrameworkElement)form));

		object currentContent = destination.Content;
		ellipseStoryboard.Completed += ((sender, e) => destination.Content = currentContent);
		ellipseStoryboard.Completed += ((sender, e) => action(parent, itemsToDelselect));
	}

	containerCanvas.Background = Brushes.Transparent;
	Panel.SetZIndex(containerCanvas, 999);

	destination.Content = containerCanvas;
}