> I'd take balkanization over the "we force-migrate everyone to the hot new thing where nothing works".

The UI framework for macOS has not changed in any substantial design-update-requiring ways since OS X was first released. They did add stuff (animations as a core concept, most notably).

The UI framework for Windows has changed even less, though it's more of a mess because there are several different ones, with an unclear relationship to each other. win32 won't hurt though, and it hasn't changed in any significant ways since dinosaurs roamed the silicon savannahs.

The UI framework for Linux ... oh wait, there isn't one.