According to this[1], musca development halted since 2009.

1. https://wiki.archlinux.org/index.php/Musca

That is not a bad thing in a window manager for people wanting an environment with few surprises. Openbox's development has been idle for years, but it where I go every time after I get bored with fighting GNOME3 or E17 on a new Linux install.

Exactly. People like to point out that older window managers aren't in active development, as if this was a bad thing. To me it just means the WM is stable and doesn't need bug fixes.

I've been migrating my Fvwm2 config (with alterations) for over a decade now. Whenever I see a new feature that's actually useful and not window dressing (ha), I generally spend a few hours to try to implement it, or my take on it. Generally, this works best when you combine it's scripting with external utilities. In this respect, it's the bash of window managers.

Surprisingly, I've actually had people be genuinely surprised as some of the simpler things, such as binding the mail key on the dell keyboard I was using to slide toggle Thunderbird in and out of view (move from off-screen on right to 90% of current screen), regardless of which desktop I'm on.