ActionWidget probably doesn't need to emit 'resize' events.
This dates back to rGOJU3ba36b9a53aa: [BREAKING CHANGE] The great and terrible dialog refactor and I can't find any evidence of it being ever used (not even in that patch, and not in that patch's history). Maybe @TrevorParscal remembers. But we could probably axe it. (It's going to be technically a breaking change, though.)