Comment 77 for bug 278471

I have the flickering with the radeon driver, a Mobility FireGL 5200 and dual monitor setup.
The flickering was on latest intrepid (with backports repository) and still is there on an up-to-date jaunty.

I could correlate the flickering of my external monitor to screen activity.
When I do nothing, the screen flickers almost not at all.
When I move a window, or switch between virtual desktops, the screen flickers more often.
When I run glxgears, the monitor stays blank until I quit glxgears.

Also, disabling desktop effects improved my situation.

With radeonhd, the screen does not flicker at all. So maybe this is related to 3D acceleration?