by SteveC1 » 29. Nov 2019, 20:12
Well, in the hopes that this information is useful, I'll add a couple of observations I just made:
I had stretched the window for display one to cover the entire screen, minus the host task bar. (So, scanning down from the top, you'd see the host task bar, the title bar for VirtualBox : 1, then the task bar for the guest...and the window frame would appear on both sides and the tool bar (or whatever it is called) for the virtual box on the bottom. It was NOT full screen mode, but sized as big as possible.
When I resumed from "saved" this morning the side borders were not present, nor were they "bled over" onto the second (physical) monitor.
During the period of time I had it (sort of) working I had noticed a tendency for the guest task bar on virtual screen one to "bleed over" slightly onto virtual screen 2. I could fix it by going into the virtual machine's display settings and dragging the right hand monitor to the right.
Just before I lost my second screen, I had noticed that the window for it on the host had somehow migradted until it was almost completely under the window for display 1; only the rightr edge was visible. It disappeared when I tried to drag it back out from under the other window and for a fleeting instant, had touched the top of physical display 2 and tried to pop into "full screen" mode as a result. (This is a feature of both linux and windows that I hate, frankly--if I want full screen, there's a perfectly good control on the title bar to do so; I don't want it "helping" me in this way when all I'm trying to do is use desktop real estate efficiently. Sometimes I'm trying to manually tile windows of different sizes, for instance.)
With that in mind I deliberately set my display one to be one of the "precanned" sizes (1680x1050 is the largest where the window and its decorations/borders still fit within a 1920x1200 monitor), closed the virtual machine (saving its state) and reopened it--I still couldn't open the second monitor. I'm about to try a complete shutdown of the VM to see what happens.
I infer from this that there seems to be something about windows on the host going full screen that causes issues.