Some compositors have a working screencopy protocol implementation but
are missing virtual keyboard and/or virtual mouse protocols. On those
compositors, don't just outright fail but instead provide a new option
to disable all remote input: --disable-input.
This is useful for using a different system (like a tablet) as
additional screen without the system providing any kind of input.
Jim Ramsay
Andri Yngvason
Consolatis
Ryan Farley