In uk.comp.homebuilt David wrote:
I have a 4K monitor with multiple inputs but haven't had the time to
understand how to get it working on these yet.

Intention was to replicate what I have at this location, which is 22" main
HD monitor in landscape and 15" second monitor in portrait.

This works well.

Haven't yet got to the stage where W10 will drive two virtual monitors
from two outputs to the single screen.

Could partition a single screen but this gets compromised if you want a
window to go full screen.

You mean 'maximise' to only go to half the screen, like it did on your two
monitor setup?

There are Windows addons to do this, which would seem easier than lying to
Windows that it has two monitors (and messy pixel scaling the monitor has to
do).

Not tried it but apparently:

WIN+Right Arrow: Resize the window to half of the display and dock it to the
right.
WIN+Left Arrow: Resize the window to half of the display and dock it to the
left.

Theo