I don't think these are the kinds of animations being referred to. They're instantaneous state changes. E.g., for the highlight effect you can just change the k

I don't think these are the kinds of animations being referred to. They're instantaneous state changes. E.g., for the highlight effect you can just change the key image on press. It doesn't need multiple frames of animation. So while it is technically an animation, I don't think it really requires any special GUI toolkit support to implement.