I wanted to create a custom control that would have the ability to have an animated part sliding out of it. My first through was to have this control have the ability to slide out in any direction (left, right, up or down), and that it had to be an adorner (to be able on slide on top of other objects etc).
And second to that was the thing that was created, was also a custom control, letting the user define what the control would content.
Animated Sliding Adorner
Please let me know if this helps you.