Sparky Backlight is a small tool which lets you change the desktop brightness via the panel’s tray icon.
The tool is targeted to small and tiny window managers such as JWM or Openbox or so, but can be used on any desktop.
sudo apt-get install sparky-backlight
Then reboot your system to load the tool to the tray.
Sparky JWM users have to add the command:
to the file:
There is a startup section on the end of the file. Then re-login or restart JWM.
Sparky Backlight uses Xbacklight which uses RandR extension.
Get more info about Xbacklight via commands:
xbacklight --help man xbacklight