I'm aware those aren't fixes, but in my understanding, xmms development is pretty much dead, so upstreaming any patches probably isn't gonna work so well, either. (And I've got the other tools on my system anyway, so that worked really nice for me, even though it obviously wasn't the right solution...)

I don't really use xmms anymore, so I haven't kept up with this, but there are at least two variants floating around; my experience is entirely with the one covered here. Someone (not sure who) has released a different build that keeps an icon in the task list... you could look around for that, anyway. (I think the difference is not in the actual build as much as the .desktop file, but there might be some difference in xmms proper as well.)