MAKE SURE TO INSTALL THIS IN YOUR HOST MACHINE, NOT INSIDE VBOX. The second solution is to simply rescale the host resolution to a lower one, so VirtualBox can function. You should notice immediate improvement in usability. A quick and easy workaround is to plug your computer into a secondary non-HiDPI monitor and move the virtual machine guest window to that screen. This results in very laggy window movement, typing, and overall updating of the screen to any changes.
3 startxfce4 failing with (EE) AddScreen/ScreenInit failed for driver 0.
