I have used a version of this called Qvwm, and even had branched it off at some point to fix some bugs... https://ahinea.com/en/tech/qvwm/ (I don't think github existed at the time or maybe I didn't know about it.)

P.S. Oh, there is the official Qvwm page: https://sourceforge.net/projects/qvwm/files/qvwm/