Had a problem with VirtualBox. It’s running on Mac OS 10.11 as the host, Ubuntu 16.04 as the guest. I couldn’t get Ubuntu to stop being in 4:3 resolution. Even though it was working before. Solution was to go to top menu bar, Devices>Insert Guest Additions CD Image, install that, and reboot. It worked. Other things that didn’t work were tell VirtualBox to use a “Hinted” resolution, trying to force the proper resolution through an option other than Auto-resize Guest Display.
September 13, 2017