Virtual Monitor Mutter/ScreenCast sources

Hey, I took a look at the mention of mutter virtual monitors in the readme.

https://gitlab.gnome.org/GNOME/mutter/-/issues/471 seems to suggests this can be done using ScreenCast. Jonas Ådahl writes "It comes down to how you intend to use it. What is needed, more or less, is that e.g. gnome-network-displays needs to use org.gnome.Mutter.ScreenCast.RecordVirtual instead of org.gnome.Mutter.ScreenCast.RecordMonitor and it'll create a virtual display for that screen cast stream."

Correct me if I'm wrong (and i very much might be), but the way i understand it basically all that would have to be done is to add a source type and the rest could mostly be handled by screencast. If I'm right, this seems like not too much trouble to implement and it would be a great addition to the project. Let me know what you thing.