Hide the HPLIP system tray icon

Currently, if you use an HP printer, you would most likely install net-print/hplip. Once it is installed with a graphical interface, an HP icon will start appearing in your system tray.

However, while it provides some nice information, it is often useless and oftentimes annoying, especially if you don't use that printer very often.

The process starts up from a desktop file called  /etc/xdg/autostart/hplip-systray.desktop. The naive thing to do is to just remove the file. Unfortunately, this means that every time an update to hplip comes out, you will need to remove the file again. This is not optimal.

The solution is to make the file ignored. This is accomplished by adding a line "Hidden=true" to it:

Once the line is added, the file contents will be ignored, and the HP tray will no longer start up.