Comment 33 for bug 293213

I can confirm this problem. Brightness keys doesn't work while they have
keycodes with Xev.

KeyRelease event, serial 35, synthetic NO, window 0x3000001,
    root 0xab, subw 0x0, time 999639, (-629,210), root:(458,235),
    state 0x0, keycode 232 (keysym 0x1008ff03, XF86MonBrightnessDown),
same_screen YES,
    XLookupString gives 0 bytes:
    XFilterEvent returns: False

KeyPress event, serial 35, synthetic NO, window 0x3000001,
    root 0xab, subw 0x0, time 1000020, (-629,210), root:(458,235),
    state 0x0, keycode 233 (keysym 0x1008ff02, XF86MonBrightnessUp),
same_screen YES,
    XLookupString gives 0 bytes:
    XmbLookupString gives 0 bytes:
    XFilterEvent returns: False