The lion kingdom has been using FVWM on Linux for over 21 years now. It's the lion form of retro computing. They might have been some of the 1st retro computing fans, before any computing was really old enough to be retro.
The lion kingdom picked FVWM because it was the window manager on SGI & it was efficient. It made a cheap PC look like an expensive SGI. In those days, SGI was something else because only they did a good job with multimedia. The trick to getting all that hardware support in those days was a more capable operating system like UNIX, so the 1st multimedia was all in UNIX.
FVWM always had a few problems:
alt-tab never alternated between 2 windows. It only cycled 1 way. You had to remember if the last action was alt-tab or alt-shift-tab to alternate. This has been the mane productivity drag for the last 21 years.
Windows can no longer be always on top.
alt-click no longer moves the window to the front.
Lions did everything they could with the config files. The next step is to try to make it work in the source code instead of config files. The mane files are in fvwm-2.6.8/fvwm/ The mane problem with fixing it in source code is you have to run it in an ssh connection to another machine. It's a lot of work for just 1 key.
The lion kingdom's 1st window manager & the one which will always be affiliated with a high end workstation is CDE. It's been open source for some time. The docker panel was utterly worthless & took up a lot of space. None of the default programs were ever used. The file manager was horribly slow. It was however smooth & expensive.
Conspicuously, the screenshots on kiwipedia show none of today's common programs: a browser, app store, word processor, & settings. They still show what UNIX supported 25 years ago, manely a command line with a graphical border.