[Lug-nuts] GTK

I'm thinking about writing a small app that uses mouse input. I could do it in Java pretty quickly, but I thought I would broaden my horizons and used GTK. I did something with Perl and GTK a very long time ago This time, I was thinking of using C. Maybe I'll explore C++ or Rust, but for such a small app, I think it is probably overkill. I never learned C++ and I'm wondering if I should invest in it or just learn Rust, That is probably for another day anyhow. My question is about GTK versions. Normally, I would just take the most recent version of GTK and go from there, but it seems like there are backwards compatibility issues. My devel system seems to have libraries for 2 and 3 at least. I just ran into a bunch of version incompatibility issues with XPRA. Am I going to have more that the usual amount of pain with GTK and should I pick a version other that 4? I am assuming I can just install 4 on the deployment system and it will happily live with the other versions. -Gary