I had a lot of issues trying to sign up. I think my display username will now be my email. But I was tired of struggling, so it'll have to do.
I did look for an answer on the forum - couldn't find one. Please direct me to it if I missed it.
Apologies if I use the wrong terminology - please inform me if I write something unclear.
I have been using VB for a while. I had two 1920x1080 displays. Everything worked fine. Today I replaced one of them with a 3840x2160 full super-super HD display (big thanks to the boss). Now the issue is that the VB window does not resize to full screen if I have the VM open with 2 displays. Some detail:
The VM correctly resizes on the larger display if it is opened with a single display
The VM does not go full screen on the larger display if I opened with two displays: The smaller display is fine, but the larger doesn't auto resize.
It can get the window on the larger display to "seem" full screen by manually resizing it. (Then I have a fine black border around the VM window where it isn't displaying - which bothers my perfectionist part a lot)
I am running on MAC OS Sierra.
Virtualbox version is 5.2.18
I have installed Guest additions. I tried re-installing it. And I removed the VM (did not delete the disc image); then created it again.
I quickly glanced through the links you provided. Thank you very much.
However the problem was fixed when I lowered the resolution to 3008x1692 - the original made everything so small I could hardly read (a bit of a bummer). And then the VB problem no longer exists on this resolution.