Don't disable second monitor when powered off/KVMed?

I’ve got a dual monitor setup connected to a Core i5 4690’s onboard graphics using two DisplayPort cables. Everything works fine in the normal case.

I now want to put a KVM switch on one of the monitors to switch it between my openSUSE machine and another machine. The idea is that I can leave “notification” content on the secondary monitor, switch the primary monitor, work on the other machine and switch back when I see a notification that needs to be dealt with.

However, as soon as I swap inputs then openSUSE decides that it is now a single monitor setup and it moves all of my windows on to the secondary screen screen.

On further testing, this also happens when I power off one of the monitors.

I understand that this is useful behaviour for a laptop connected to an external display, but it isn’t helpful on a static desktop setup! Is it possible to make Gnome/XOrg keep a dual-screen setup, even when one of the screens gets powered off/switched by KVM?