Some hotkeys are handled by gnome-power-manager. Others are handled elsewhere (e.g. in hardware).
Experiment with using the brightness keys at the vt console, with and without X running. Experiment with them in X but with gnome-power-manager shut off. Use xev to see what key codes (if any) X sees. Here's a xev command string that makes the xev easier to read:
xev | sed -n 's/^.*state \([0-9].*\), keycode *\([0-9]\+\) *\(.*\), .*$/keycode \2 = \3, state = \1/p'
More info on debugging hotkey issues is available at this link:
If the problem is in a binary application like gnome-power-manager or pm-utils, you may find strace output of it to shed some light.
If it's a hal problem, then comparing lshal output before and after the brightness hotkey is hit might be worth looking at; in theory the lshal output should be identical, so if there is any difference it might hint that the problem lays deeper down.
On some systems there are scripts from acpi-support that play a role in handling the brightness keys. These are in /etc/acpi/. I have a Dell laptop too, and these scripts don't have an effect for me, so I'm guessing this is unlikely to be the case either for you, but I don't know the specifics of your hardware so it's certainly a possibility.
Some hotkeys are handled by gnome-power- manager. Others are handled elsewhere (e.g. in hardware).
Experiment with using the brightness keys at the vt console, with and without X running. Experiment with them in X but with gnome-power-manager shut off. Use xev to see what key codes (if any) X sees. Here's a xev command string that makes the xev easier to read:
xev | sed -n 's/^.*state \([0-9].*\), keycode *\([0-9]\+\) *\(.*\), .*$/keycode \2 = \3, state = \1/p'
More info on debugging hotkey issues is available at this link:
https:/ /wiki.ubuntu. com/X/Troublesh ooting# Problem involves missing support for some keyboard keys
If the problem is in a binary application like gnome-power-manager or pm-utils, you may find strace output of it to shed some light.
If it's a hal problem, then comparing lshal output before and after the brightness hotkey is hit might be worth looking at; in theory the lshal output should be identical, so if there is any difference it might hint that the problem lays deeper down.
On some systems there are scripts from acpi-support that play a role in handling the brightness keys. These are in /etc/acpi/. I have a Dell laptop too, and these scripts don't have an effect for me, so I'm guessing this is unlikely to be the case either for you, but I don't know the specifics of your hardware so it's certainly a possibility.
Hope this helps