Earlier quoted context omitted.
> They just haven’t done it. Literally nobody has done it. It's beyond ridiculous that you can't already show or duplicate an application window on any display you want and allow it to be controlled from anywhere it is visible. Searching for ways to do this lead one into extremely niche software ecosystems. Please is there any collaboration app out there that makes it seamless to toss windows around like everyone act…
I feel like multiple people did it back in the original X11 days, and almost certainly when compiz was the new hotness
Even classic Mac OS, which wasn’t designed to be “rootless” could be run that way could have its windows mixed with OS X windows in the classic days.
As others have pointed out, there is already a PoC app that is doing it, so it seems if Apple wants to, it’s completely in their power. However, does this match their vision? (pun intended) Time will tell.