1. acpi event listener - translate to e internal messages (e_msg)
   (especially button/lid, ac_adaptor, battery, sony/hotkey s1, av mode,
   brightness +, brightness -, sleep, wifi on/off)
   
acpi_listen is a good one (unix socket /var/run/acpid.socket - just cleartext
newline by newline)

2. /proc/acpi/**/**/.../*/brightness controls
   (look at sony and asus - different)

XF86XK_Standby
XF86XK_MonBrightnessUp
XF86XK_MonBrightnessDown
XF86XK_PowerDown
XF86XK_PowerOff
XF86XK_WakeUp
XF86XK_Sleep
XF86XK_BrightnessAdjust
XF86XK_Display
XF86XK_LogOff
XF86XK_Battery

