x11-wm/
fvwm

An extremely powerful ICCCM-compliant multiple virtual desktop window manager

https://www.fvwm.org/

There are no pull requests

You think something is missing here?
Start with filling a new pull requests.

If you also like to help the Gentoo project, you can consider sending a Pull Request via GitHub.
Before doing so, you might want to take a look at the wiki page.