I'm developing extension for wingpanel-indicator-power which allows you to change the screen brightness directory from the indicator.
The the moment this is only possible by accessing the power options from switchboard.
For now it is working quite well.
But at the moment, this extension is displayed all the time, even if you are using a desktop computer, where it is not possible to change the brightness.
I want to check if user is using a notebook and only display the brightness-slider, if it is not a desktop computer.