I was suggesting that /etc/X11/Xsession.d/98vboxadd-xclient should do the same in_virtual_machine check, which I indeed adapted from what you currently do in /etc/init.d/virtualbox-guest-utils
I was suggesting that /etc/X11/ Xsession. d/98vboxadd- xclient should do the same in_virtual_machine check, which I indeed adapted from what you currently do in /etc/init. d/virtualbox- guest-utils