I'm trying to change the brightness steps in XFCE from 10 to 20. I'd like the ability to gradually change the laptop's brightness by 5% instead of 10%. Is there a way to set this up with a config file for XFCE?

If that is not an option, I have thought of another way: I know that I can disable XFCE's power settings from handling brightness keys, but setting up a shortcut in keyboard preferences does not seem to be able to override this.

Is there another way I can remap what XF86MonBrightnessUp and XF86MonBrightnessDown do when pressed? Specifically, I'd like Up to use the command lumeus +5% and Down to use the command lumeus -5%.

Can either idea be done while using XFCE with its XFWM?

6 Answers 6


No need to recompile the xfce4-power-manager

There really is no need to recompile xfce4-power-manager.

Firstly, install xbacklight

$ sudo apt install xbacklight

Secondly, check whether you have control over the backlight.

$ xbacklight -1
$ xbacklight +5

Should these commands result in a No outputs have backlight property error, then follow these remediating steps before proceeding.

Once xbacklight -1 and xbacklight +1 work from the command line, proceed with assigning these commands to respectively the XF86MonBrightnessDown and XF86MonBrightnessUp keys. This is done by hitting those keys when asked by the Settings → Keyboard → Application Shortcuts application.

Finally, reboot for these changes to take effect.

Keyboard settings


Another year passes and another year of no progress on this issue despite easy solutions posted online (e.g., How to obtain more brightness levels using Fn+keys in Xfce?).

You need to recompile Xfce Power Manager with minor changes in the code.

  1. Download Power Manager from here: http://archive.xfce.org/xfce/4.12/src/xfce4-power-manager-1.4.3.tar.bz2

  2. Unpack it and cd into the folder.

  3. Open common/xfpm-brightness.c in a text editor:  (e.g., gvim common/xfpm-brightness.c).

  4. Change line 515:

    set_level = MAX (hw_level/1.5, brightness->priv->min_level);
  5. Change line 475:

    set_level = MIN (hw_level*2 + (hw_level==0), brightness->priv->max_level );
  6. Save and close.

  7. Type ./configure at the command prompt. You're kind of on your own here... there will be errors and you need to fix them. E.g., on Xubuntu 18.04 I needed to install several things:

    sudo apt-get install libdbus-glib-1-dev
    sudo apt-get install libxfce4ui-1-dev
    sudo apt-get install libnotify-dev
    sudo apt-get install libupower-glib-dev
  8. Once configure is complete, type make.

  9. Once make completes, type sudo make install.

  10. Logout and login. Voilà! You have smaller backlight increments.

  • Or in one go for Xubuntu LTS 18.04: sudo apt install libdbus-glib-1-dev libxfce4ui-1-dev libnotify-dev libupower-glib-dev intltool Oct 1, 2018 at 22:33

Before downloading (step 1 above), check the version number:

xfce4-power-manager --version

Then download the correct version from here:


Last issue, I seem to run into a polkit error when running the custom xfce4 power manager (related to [this][1] but no fix).

[1]: Authentication needed to run xfpm-power-backlight-helper as super user https://forum.xfce.org/viewtopic.php?id=11190


I'm on arch and recompiled xfce4 power manager as proposed. I also had the polkit problem after installing the compiled power manager. Here is how I solved it so that everything works with customizable brightness steps, the exponential option and the Fn key combination:

  1. git clone https://github.com/xfce-mirror/xfce4-power-manager
  2. cd xfce4-power-manager
  3. git checkout master; I'm on commit ID eee63912efb5b3d01000c63bd306b4a629ec6f7f which is basically some commits ahead of v1.6.1.
  4. wget https://bugzilla.xfce.org/attachment.cgi?id=7728 -O brightness.patch
  5. git apply brightness.patch
  6. ./autogen.sh
  7. make
  8. sudo make install
  9. reboot
  10. now authentication is asked when using Fn+Brightness control keys; that is because the path of xfpm-power-backlight-helper has changed
  11. sudo vim /usr/share/polkit-1/actions/org.xfce.power.policy
  12. change the XML node

<annotate key="org.freedesktop.policykit.exec.path">/usr/bin/xfpm-power-backlight-helper</annotate>


<annotate key="org.freedesktop.policykit.exec.path">/usr/local/sbin/xfpm-power-backlight-helper</annotate>


ub_marco’s answer almost solves it for me.  After sudo make install finishes the installation, I need to edit the file org.xfce.power.policy through this command:

sudo vim /usr/share/polkit-1/actions/org.xfce.power.policy

and change the following lines in the file:

 <annotate key="org.freedesktop.policykit.exec.path">/usr/local/sbin/xfpm-power-backlight-helper</annotate>

 <annotate key="org.freedesktop.policykit.exec.path">/usr/local/sbin/xfce4-pm-helper</annotate>

so that they point to /usr/sbin rather than /usr/local/sbin.

Each time I recompile, I need to re-edit this file.  Some path must be wrong in the Makefile, but I can't track it down.


Usually, if you install some other packages together, the brightness and sound keys should work without any configuration:

sudo apt update
sudo apt install xfce4-goodies xorg dbus-x11 x11-xserver-utils

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