I tried in openSUSE to set a global shortcut for the function keys, but it’s not reading the press of the “Fn” key. If I press the “Ctrl” button, it reads that, but the function key is never read by it.
IIRC, it’s always been that way. I encountered similar with openSUSE 12.2, KDE 4.8 whereby a (kernel?) regression meant that my screen brightness keys (fn+9,fn+10) weren’t working. My workaround was to create keyboard shortcuts for ‘KDE Daemon’. I had the same limitation and had to assign CTRL+9, CTRL+10 instead.
Of course, you now want to assign the brightnes keys (Fn F9 and Fn F10) to these actions. The easiest way is to go to the KDE systemsettings and open ‘Shortcuts and Gestures’. Then follow these steps (or import the khotkeys file I created instead):
Create a new global shortcut (on the bottom: edit > new > global shortcut > command/URL
) and call it ‘backlight off’