What fools Apple engineering management must be, then!

Compositor work isn't tremendously hard when the graphics primitives are already done.

UI state handling and input is a majority of the work from there. I've implemented this work before. A large portion of my background is in compositors and UI primitives.

What's really cool about having window backing layer handles, is you can do all sorts of crazy fun stuff in the office and show off to your coworkers or tech demo that basically will never make it to production because it's totally impractical.

The best example of that which actually did end up in a final product in my opinion was Windows Flip 3D. Totally fun implementation, I'm sure.

Try it with a full suite of Mac Apps and you’ll find it falls apart because they aren’t all well behaved.

You are making this sound much more complicated than it really is.

The trivial case is simple. You are imagining it's all the trivial case.

Remember the original comment was the claim that Xorg could easily do remote windows years ago. This is only true using the low performance path that modern operating systems have universally rejected.

In fact, there's already a project for it on GitHub. https://github.com/saagarjha/Ensemble

480 lines total, including comments, headers, whole shebang.

It's all of the edge cases and UX refinements that takes time.