@Chris and Cyril: I'm a bit confused, I'm not a linux expert and I thought I did it right but obviously not. Now I tried again showkey -k and showkey -s and in both cases I see keycodes, however in completely different styles. Here my results:
1. showkey -k
Brightness on/off keycode 148
Wireless on/off keycode 238
Monitor Switch keycode 431
Mail? (Fn+F7) keycode 149
Internet? (Fn+F8) keycode 202
Each time it shows one for press and one for release
@Chris and Cyril: I'm a bit confused, I'm not a linux expert and I thought I did it right but obviously not. Now I tried again showkey -k and showkey -s and in both cases I see keycodes, however in completely different styles. Here my results:
1. showkey -k
Brightness on/off keycode 148
Wireless on/off keycode 238
Monitor Switch keycode 431
Mail? (Fn+F7) keycode 149
Internet? (Fn+F8) keycode 202
Each time it shows one for press and one for release
2. showkey -s
Brightness on/off 0xe0 0x1f 0xe0 0x9f
Wireless on/off 0xe0 0x73 0xe0 0xf3
Monitor Switch nothing shown
Mail 0xe0 0x17
0xe0 0x97 (here it shows 2 lines)
Internet 0xe0 0x2b 0xe0 0xab
I hope this helps and sorry that I did not make it right the first time.