OK sheesh, THIS was a super-sweet spot in my (admittedly ancient) computing platform history: DESQView and QEMM.
https://en.wikipedia.org/wiki/DESQview
I mistakenly remembered it as OS/2, which I did run around that time (88, 89, 90) but no, it was desqview.
I'm fine without a mouse, it turns out. I've been writing a bunch of CP/M sofware and old workflows came back (hint: its barbaric, I don't fully recommend it).
Gonna put a web page up about the CP/M thing soon. Got my version 2 boards from JLCPCB, awaiting a delayed delivery from Digikey.