org.gnome.Mutter.DisplayConfig contains a new property that tells
whether apply will be allowed to be called or not. Whether it is true or
not depends on policy stored in any of its monitors.xml configuration
files.
In order to make it clearer that configuration is not possible, except
for night light, make sure to hide the unconfigurable parts, leaving
only night light.
This will allow us to switch the display panel away from using the
GnomeRR api directly in order to gracefully move to a new DBus display
configuration API to be provided by mutter while still keeping the
existing functionality on top of the GnomeRR api while the new one
is developed.
https://bugzilla.gnome.org/show_bug.cgi?id=782785