When using a the qxl driver (for virtual machines), we'll be getting resizes of
the display by changes on the preferred output id.
The status quo is that if one runs xrandr --output Virtual-0 --preferred after
resizing the screen, kscreen will be set on the right outputId and just work.
This shouldn't have an impact on normal use-cases because it's very strange that
the preferred mode changes at runtime.

Ran it on my laptop, nothing broke. Will test on QXL in a bit.