[ltp] Debian Wheezy w/XFCE screen brightness step value

[Nate Bargmann]

* On 2012 21 Feb 09:04 -0600, Henrique de Moraes Holschuh wrote:
 
> You can actually ask thinkpad-acpi to rat out the PIDs of processes messing
> with brightness values [through thinkpad-acpi], check the documentation.

I managed to do that by reloading the module as per the docs:

$ sudo  modprobe thinkpad_acpi debug=0x8000

This allows debugging of PIDs.  However, on this Debian system I finally
found the output in /var/log/auth.log!  Huh?  Whatever.  I guess it uses
policytkit to handle the event.

What I found is:

Executing command [USER=root] [TTY=unknown] [CWD=/] [COMMAND=/usr/sb
in/xfpm-power-backlight-helper --set-brightness 3]

Which led to Debian bug report 627336:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=627336

Which, in turn, leads to this XFCE report:

https://bugzilla.xfce.org/show_bug.cgi?id=7541

Comments 13 and 15 describe how to disable xfpm from handling the
backlight.  I used the following commands:

$ xfconf-query -c xfce4-power-manager -n -t bool -p
/xfce4-power-manager/change-brightness-on-key-events -s false

$ xfconf-query -c xfce4-power-manager -n -t bool -p
 /xfce4-power-manager/show-brightness-popup -s false

I can report that the eight brightness levels are restored by the first
command and the OSD is disabled by the second.

I do recall that GNOME had the same issue and probably requires a
similar "fix".

- Nate >>

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