Code

node123 = e.Source as DiagramNode;

	     ScaleTransform scale = new ScaleTransform();
	     scale.CenterX = node123.Bounds.X - node123.Bounds.Width / 2;
	     scale.CenterY = node123.Bounds.Y - node123.Bounds.Height / 2;

	     originalTransform = node123.RenderTransform;
	     TransformGroup tg = new TransformGroup();
	     tg.Children.Add(originalTransform);
	     tg.Children.Add(scale);
	     node123.RenderTransform = tg;

	     var xa = new DoubleAnimation(2, 1, new Duration(new TimeSpan(0, 0, 0, 0, 500)));
	     var ya = new DoubleAnimation(2, 1, new Duration(new TimeSpan(0, 0, 0, 0, 500)));

	     if (diagram.FindName("mouseLeave") != null)
		   diagram.UnregisterName("mouseLeave");
	     diagram.RegisterName("mouseLeave", scale);

	     Storyboard.SetTargetName(xa, "mouseLeave");
	     Storyboard.SetTargetProperty(xa, new PropertyPath("ScaleX"));
	     Storyboard.SetTargetName(ya, "mouseLeave");
	     Storyboard.SetTargetProperty(ya, new PropertyPath("ScaleY"));

	     var sb = new Storyboard();
	     //sb.AutoReverse = true;
	     sb.Children.Add(xa);
	     sb.Children.Add(ya);
	     sb.Completed += new EventHandler(sb_Completed);
	     sb.Begin(diagram);