It's reproducible every time for me right now, simply moving windows to the second screen makes them disappear from the window list. I've got detailed notes on how I configured Ubuntu if they are needed. The basic setup is that I'm running on an ATI Radeon x1950, I installed the Ubuntu ATI drivers, then the latest ATI drivers, and configured it for dual screen using the following aticonfig commands: aticonfig --dtop=horizontal aticonfig --initial --desktop-setup=horizontal --overlay-on=1 --ovt=Xv If you have any problems reproducing this let me know, I plan to re-install Ubuntu anyway soon to check that my notes are accurate, so it's no problem to test that it's 100% reproducible. Wnckprop results from a console window on the second monitor are: Name: Bottom Expanded Edge Panel Icon Name: Bottom Expanded Edge Panel Icons: set On Workspace: 0 ('Desk 1') On Screen: 0 (Window Manager: compiz) Window Type: dock or panel Geometry (x, y, width, height): 0, 1000, 1280, 24 Class Group: Gnome-panel XID: 16777219 PID: 5958 Session ID: State: sticky, skip pager, skip tasklist Possible Actions: make above, unmake above, make below, unmake below I've attached a screenshot of my entire desktop, showing the windows on each monitor, and clearly showing the difference between the window list and the window selector. Ross > From: