Language, OS and GUI -independent windowing API provided as a virtual filesystem (fornaxis.org)

Reminds me of Tagsistant's FUSE-based tagged-filesystem API, which touts full compatibility with graphical file -managers and -sharing protocols as a major advantage.

Simpler than, but somewhat reminiscent of, Plan 9's windowing system https://man.cat-v.org/plan_9/4/rio

Last updated 2014-07-03

So I guess (2014) is missing.

Qtile have it since start, build upon it so it is very flexible to extend and it is in python

> A prototype of FORGE is implemented in MacRelix; a port to FUSE is in progress.

MacRelix was recently featured on hn. It is a Unix-like environment for classic Mac OS.