At some point I became slightly obsessed with Xenix, and spent months trying to compile X11R4 from sources, all in vain [1]

Then I stumbled upon MGR, and soon I had a working windowing system. Quite impressive.

The only quirk being, since I was using a virtual machine instead of a 486 or so, I had to connect a serial mouse to my MacBook using a serial to USB adaptor, and then forward the mouse to the VM, as MGR did not have drivers for PS/2...

[1] If you wanna give it a shot, get in touch with me... :)

Curious that this doesn't sound compatible with X, but in the screenshot there's certainly something that looks like xeyes and xclock running.

Xeyes and xclock were probably ports or variants of programs that had existed on Unix window systems since forever ago.

I think Windows 3.1 also had something like xeyes. It might have been part of an add-on pack, but I remember it existing. Maybe putting eyes on screen to follow a mouse was an early Hello World for GUIs.

There is an mgr-specific program called "mgreyes.c" included in the source tarball. So it was probably a from-scratch clone.