Night Color not working in guests

[Julian Stecklina]

Hello everyone,

we noticed that any of the Night Color modes in Gnome and KDE don't work in
guests when they run with vGPUs. This is pretty easy to reproduce: Pick a GNOME
or KDE Live CD and try to enable Night Color (KDE) or Night Light (GNOME).

This is a bit of a minor issue, but I wonder what would be missing to make this
work. Is there anything missing in Qemu or this is something that the mediator
needs to handle. Does anyone have an idea?

Thanks,
Julian