Very cool, hard to imagine the constraints they had when that was created. Reminds me of an interview I heard with Bill Joy a while back (creator of vi + worked on the Java language in its beginnings).

"We solved problems that do not exist anymore" — Bill Joy.

Constraints? It was generally developed on '3-M' machines: more or less around 1MIPS of processing power (68k, VAX), 1M of memory, and 1M pixels (e.g. 1024x1024).

While X11 is pretty grokky these days and definitely showing it's age, I'm not sure that the problems X11 solved don't exist any more. In particular, the idea of running an app on one machine and displaying it more or less transparently. It's just that with very performant desktops, this became the exception rather than the norm.

Solution: X11-over-websockets with display in Javascript.

(Actually now wondering whether this nonsense already exists?)

There's a similar thing for Wayland too: https://github.com/udevbe/greenfield

And GTK has yet another way to do this built-in, that uses its own protocol: https://developer.gnome.org/gtk3/stable/gtk-broadway.html