@PragTob Thank you for the excellent clarification! I understand and I find that Ruby has some amazingly powerful features compared to my previous programming languages (C, C++, C#, Java).

I think I can put radio_groups into Swt::App. There is a Swt::Common::Child mixin module that I could use for accessing Swt::App, but it appears to be broken in some classes because it doesn't climb the parent tree. I'm not sure the mixin is actually used for anything because if I comment out its app method, all tests still pass. So I guess we should either get rid of it or add tests and make it work properly. Thoughts?