[sillystuff]

Even if you are sandboxing, you can do that with X. Just put the sandboxed app into a nested X server. Some sandboxing apps like firejail make it trivial to do this using xpra as the nested X server.

I wish Wayland had been more ambitious. Without a standard shared server that window managers can run on without implementing their own compositor, it is just duplication of effort, and a mess of incompatible ways of doing things; I suspect this was intentional to create a higher bar for "fragmentation", but what a mess. It will be even worse when Wayland on non-linux becomes a thing, since most WM/DEs with Wayland support are using Linux specific d-bus to work-around Wayland limitations.