Excepting crashing bugs development depends a bit on when people have time or a need for a new feature but Fluxus is indeed still actively developed. As I see it it's indeed "done" in the sense of being useful for it's intended purpose right now, but there is space for big improvements like redoing the editor itself in Scheme, morefunctionality in the Windows version, etc. I'm personally working on and off on a little library for new ways of interacting with generative music in it. We're alive and well, I'd say.