It looks like my native derivation of Button just uses the default constructor to establish those bindings. That’s not to say that there isn’t a way to do it from blueprint, I’m just not seeing it.
I don’t know if that is a fair “criticism”. Even with OOP there is the distinction between things you are and things you have. With most widgets it generally makes more sense to build them up through composition to have other widgets. Based on the behavior you’re adding to your button it’s worth asking “Could this really be given to another client that is expecting a button?”. I’m not really sure that is true given the toggle nature you’re adding. But design is in the eye of the beholder a bit. Good luck!