Ubuntu 14.04 host is running virtualbox 4.3.34_Ubuntu r104062. There is an ubuntu 15.10 client which, when running, has a small window size. And it will not expand to full window when using the virtualbox -> View -> Switch to Fullscreen. How can this be fixed?
The standard solution to this is to install vboxadditions and reboot, then try it again. (for instance see http://ubuntuforums.org/showthread.php?t=1042494 ) But this does not work.
When I examine the vboxadditions install messages, there is the following:
Verifying archive integrity... All good. Uncompressing VirtualBox 4.3.10 Guest Additions for Linux............ VirtualBox Guest Additions installer Removing installed version 4.3.10 of VirtualBox Guest Additions... Copying additional installer modules ... Installing additional modules ... Removing existing VirtualBox non-DKMS kernel modules ...done. Building the VirtualBox Guest Additions kernel modules The headers for the current running kernel were not found. If the following module compilation fails then this could be the reason. Building the main Guest Additions module ...done. Building the shared folder support module ...fail! (Look at /var/log/vboxadd-install.log to find out what went wrong) Doing non-kernel setup of the Guest Additions ...done. Installing the Window System drivers Warning: unknown version of the X Window System installed. Not installing X Window System drivers. ...done. Installing graphics libraries and desktop services components ...done. Press Return to close this window...
I am wondering if the "unknown version" warning in the install has something to do with the issue?