As usual Nvidia driver messed up the brightness keys.
Now it's not working in KDE and Gnome. When I use F1 and F2 keys sure enough I see the bar moving...but no brightness change. Sound keys work though. I use Macbook Pro

Strange thing is I can change the brightness using...

echo 2 > /sys/class/backlight/mbp_backlight/brightness

But not from graphics terminal !!!

I have to use Ctrl+Alt+F2 and go to non-gui terminal and then punch in the above command. That changes brightness and again go back to graphics one.

Sometimes when the brightness starts with 0 setting, so there is no way to see anything on the screen but restart the system into text mode change the brightness and then switch to GUI. Too much work......any ideaz???