Comment #4 on issue 413 by norbert.zeh: Windows don't disappear http://code.google.com/p/xmonad/issues/detail?id=413 I ran into the same problem just now. Same setup: xmonad darcs, arch linux, feh for setting the background, NVIDIA dual screen. The caveats on the background actually looked like *parts* of me emacs window, each with nicely rounded corners. Really strange. Since I never had this problem using Debian on the same hardware before, nor using arch on a single screen with an ATI graphics card, I am inclined to think that this is not an xmonad issue and maybe blame the new X server in arch, the bleeding edge NVIDIA driver or something like that. I may of course be completely off with this guess and would still like to know what causes this behaviour and how to fix it.