Missing "Favorite" callback

I'm not sure if this is a bug or a missing feature (and hence this should became a suggestion), but if I'm not logged and I try to favorite an instructable, then the site will ask me to login. So far so good. But the callback on the instructable doesn't contain any information about the user action, and so it wasn't automatically favorited.

I find this quite frustrating, since I'm not a big user and I'm usually not logged when I surf the site..