Dithering causing flickering: desktop image 'etched' on screen
This was somewhat disturbing - even after rebooting, I could see a faded image of a Firefox window in all virtual terminals! (Which obviously should have been all black.) After about 2 minutes it had faded away. Phew. I presume this is not good for the hardware so won't be repeating it.
What happens normally: after installing Fedora 16 and updating to driver 290.10, the screen sometimes flickers. Simply moving windows around in Gnome (fallback mode) can start and stop this. This seemed to be solved by changing the dithering to 8bpp or just disabling dithering. I was planning on setting this automatically in a config file but hadn't got around to it.
What happened today: I forgot to change the dithering as above and then went away. The power saving blanked the screen. I came back but could do nothing to prevent the screen from flickering. The shadow of a Firefox window could be seen on other desktops and VTs. As mentioned, it could still be seen in VTs after rebooting.
The screen is a RGBLED LCD on a Dell Precision M4600 laptop with BIOS revision A07. Perhaps its support for 10bpp is something to do with the issue. Bug report info attached. Also /var/log/messages attached for the problem session, in case it contains anything useful.