IMO there's a more general problem with how easy it is to extend widgets in a toolkit when you make use of a scripting layer on top of the toolkit. Even with a

IMO there's a more general problem with how easy it is to extend widgets in a toolkit when you make use of a scripting layer on top of the toolkit. Even with a nice API, it's difficult to cover all the edge cases when the C/C++ vs high level language barrier exists. The only non-trivial Ruby based GUI I've built has ended up with a custom toolkit as a result of trying to avoid these sorts of API barriers. The building a new toolkit without the API barrier does result in some lost functionality, some NIH syndrome, but it does provide a bunch of extra flexibility.