You would have thought after 40 years there would be some standard GUI toolkit all the major OSes would adopt but stuff like swing, html, and TCL/tk are all we have...
and of course vt100 escape sequences for some reason.
I guess not globally adopted but Qt to me is a pretty workable cross platform solution, nicely performant and reasonably easy to work with with great community support and problem googleability as well as pretty damn nice docs.
Well, the idea between "major OSes" is that they try/do/offer different things. And the UI is large part of that. If they all have adopted the same, we might as well use a single OS.
That said, there should have been one, good, cross platform GUI toolking, and Qt, for various reasons, isn't it. The best we have is Electron...
I think an option could be GPU-accelerated drawing. It won't look native, but one can create a UI that performs well on just about any platform. Vulkan greatly improves the portability of such applications (compared to the OpenGL vs. OpenGL ES mess), and Skia has a nice set of primitives on which one could build.
It's also worth pointing out that creating a cross-platform API is better for new players than for entrenched ones.
You're just inventing your own toolkit, which is going to end in tears for everyone since you will have to recreate every component from scratch, rediscover all the interesting edge cases thereof, fail to reimplement some expected behaviors (triple-click text selection, drag-scroll, whatever), and break every accessibility tool in the process.
and of course vt100 escape sequences for some reason.