A bug of demo app: animation name isn't updated

[luqiming666]

Steps to reproduce:

1. add an animation;
2. delete this animation;
3. add a different animation

End-result: the very first animation name is shown instead of the newly added one. I created a fix on my forked branch, as below:

public void bindTo(CustomAnimationBody animationBody) {
            binding.getModel().setAnimationBody(animationBody);
            binding.invalidateAll();
}