How can I avoid black stripes in the top and bottom of the screen when running Virtual Box full screen mode in an external monitor? See the screenshot below.
The external monitor has resolution 1920 x 1200 (aspect ratio 16:10). The internal screen has resolution 1920 x 1080 (aspect ratio 16:9).
I've tried to re-install Guest Additions, switch between normal and fullscreen modes,
VBoxManage setextradata "Windows 10" "CustomVideoMode1" "1920x1200x32" etc. but nothing helps.
Host: Dell Precision 7510, Radeon HD 8890M, Debian Linux Stretch 64-bit, Xfce 4.12, VirtualBox 5.2.18
Guest: Windows 10 Pro 1809 64-bit, VirtualBox Guest Additions 5.2.18