How to stop gnome-power-manager from changing the global backlight setting?

Solution 1:

It seems this can only be disabled by editing a gconf setting using gconf-editor or the command line tool gconftool-2 (easier). As GDM is run by a special user (gdm), you got to disable it for the desktop user and that special user:

Run the following from a gnome-terminal:

gconftool-2 --set --type boolean  "/apps/gnome-power-manager/backlight/enable" false

This will deactivate the backlight control for your user. Now type:

sudo -u gdm gconftool-2 --set --type boolean  "/apps/gnome-power-manager/backlight/enable" false

This will deactivate the backlight control for the user that controls the GDM screen.

You should now no longer see automatic backlight level changes.

In Ubuntu 11.10 Oneiric Ocelot this changed to:

 gsettings set org.gnome.settings-daemon.plugins.power idle-dim-ac false
 gsettings set org.gnome.settings-daemon.plugins.power idle-dim-battery false

Still not sure how to disable it for the login screen.