I think the problem is that nobody wants to do a lot of work to make something that will be basically just good enough for hobby projects. There's no money in i

I think the problem is that nobody wants to do a lot of work to make something that will be basically just good enough for hobby projects. There's no money in it, and side projects "for personal fulfillment" tend to avoid the kind of clerical work that compatibility with several different APIs requires: lots of reading, lots of boilerplate (on the framework end), lots of testing, not much freewheeling design and speculation. Hell, IUP (which supports Windows and Gtk) has gone decades without finding someone outside Brazil to maintain a Cocoa port. It's either professional-grade — very complex and needing a corporate backer — or it's not, and a GUI cross-platform compatibility layer is in the uncanny valley. Maybe someone will figure out how to fund it?