Excerpts from Alexey Feigin's message of Thu Oct 15 00:07:46 -0600 2009:
Normally I use xmonad with gnome. When I connected the second monitor and configured xorg.conf with Xinerama, the second monitor just shows the background and I can't move any windows into it. I can move my mouse into it and select things from menus in the gnome bar, but the windows always appear on the primary monitor. (Also, the second monitor appears to have a second mouse, with a cursor that looks like an X, not the gnome cursor.)
I'm on Ubuntu 9.04 with xmonad 0.8. The video card is ATI Radeon HD 3450 (using fglrx).
There are two sections in the FAQ on the wiki that might help: http://haskell.org/haskellwiki/Xmonad/Frequently_asked_questions I would start with the Configuration/Multi-head & Workspaces one, to see if mod-w mod-e, mod-shift-e, etc., and workspace switching works as it's supposed to. If not then you could go to the Multi-head troubleshooting part to make sure your haskell x11 was compiled with xinerama support, but I suspect that your haskell setup is okay, from what you describe. If default xmonad screen and workspace handling isn't working correctly I'd suspect your multi-head is actually not in a xinerama configuration but rather using separate X displays. Unfortunately I know nothing about ATI xinerama configuration, hopefully others can step in if that does turn out to be the problem. regards, -- wmw