Comment 1 for bug 192009

I'm fairly certain that I've been bitten by this as well. I have a dual head radeon card. When enabling the secondary display, both the upper and lower panels switch from my primary monitor to the secondary monitor. I am running an up-to-date Hardy i386 development release as of 22 March 2008.

libxrandr2 2:1.2.2-1
gnome-panel 1:2.22.0-0ubuntu2
metacity 1:2.22.0-0ubuntu1
xserver-xorg-video-ati 1:6.8.0-1