Yes, removing /usr/share/X11/xorg.conf.d/50-qxl.conf fixes the VirtualBox X issues.
Options:
- no longer install qxl-xorg-enhance in images build by me by default
- make 50-qxl.conf somehow not interfere with VirtualBox
This is kinda in a rush because I want to release Whonix 13.
I don’t know how to handle such cases in future. If after proposing such changes by one virtualizer maintainer to test if it breaks other virtualizers.