
`gdctl show` now prints "monitor preferences", which currently consists of only the luminance setting. `gdctl prefs` is introduced, where one can run e.g. `gdctl prefs --monitor DP-1 --luminance 80.0` to set the output luminance of the monitor connected to DP-1 to 80%. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4271>