Comment 21 for bug 527157

Here's a thread in the linux-thinkpad mailing list about this issue (it affects XFCE as well as GNOME):
http://mailman.linux-thinkpad.org/pipermail/linux-thinkpad/2012-February/050576.html

The thinkpad-acpi kernel module maintainer says:
> This typically means broken crap that reacts to brightness *change* events as if they were keypresses.

Upstream bugs that seem related to this:

- ThinkPad X60s and X300, improper brightness adjustment using function keys Fn+{Home,End}, twice long step
  https://bugzilla.gnome.org/show_bug.cgi?id=579224

- Need a setting to tell g-p-m that brightness changes are handled in hardware when using xrandr
  https://bugzilla.gnome.org/show_bug.cgi?id=601410