Introduction

For months (years?) I have wondered why my ThinkPads fail to turn the backlight off when the screen is locked (blanked).

Solution: xset dpms force off in a Script

Unforunately, I found no way to get the X system to turn the backlight off.

The only way to turn it of is to use xset to switch the screen off.

An according lock script might look like this:

#!/bin/bash
 
# activate screensaver
xscreensaver-command -lock
# or: gnome-screensaver-command --lock
# or: slock
# or: xlock $*
 
# let the screen fade out
sleep 4
 
# switch the screen off
xset dpms force off
 

Xfce4 integration

The script solution above has one disadvantage: The script needs to be called. Time based screen locking and Xfce's "lock screen" button won'nt use it.

Fortunately, Xfce4 uses a script anyway, in the first place: /usr/bin/xflock4

One can simple edit this file (as root), and insert the xset call right before the final exit:

#[...]
 
# begin of change
 
# let the screen fade out
sleep 4

# switch the screen off
xset dpms force off
 
# end of change
 
exit 0

Of course this edit has to be re-done after an upgrade that provides a fresh original version of xflock4.