One of the common use cases for laptops is to plug into an external display at a docking station or with a projector, and unplug and use the internal display, then plug into another external display, then later back to the internal display, and keep on cycling like this. Unfortunately, Linux distributions haven’t supported switching displays very easily.

Enter disper to save the day. This is a command-line (and so easily scriptable) tool to switch the display in use. For example, to make only the internal display active, run disper -s. For only the external display, disper -S. And to toggle between them, disper --cycle-stages='-s:-S' -C. So when I want to bind one of the special laptop function keys to alternate between external-display-active-only and internal-display-active-only in Gnome, I run gnome-keybinding-properties, add a custom shortcut to run disper --cycle-stages=-s:-S -C, and bind that to XF86LaunchA. Voilà, with one keypress I can switch between the laptop’s screen and the projector. Other flags to disper let you activate both displays, etc.