I've installed Fedora 18 64bit guest into a Virtualbox VM running on a Max OSX host. Previously I've installed Fedora 17 and after installing guest additions from the rpm fusion repo full screen mode worked by resizing to the same resolution as the host machine.
However on Fedora 18 after installing guest additions and running in full screen mode the guest runs at 1024x768. The host is running at 1366x768. This results in two large black bars on the left and right of the guest when in full screen mode.
Is there a way to alleviate this? Perhaps to get Fedora to run a custom resolution?
*Edit*The root of the problem was that GuestAdditions was failing to install. After trying to build it manually and using the version from RPM Fusion I was unable to solve this. I've downloaded Fedora 17 and the version of GuestAdditions from RPM Fusion works fine with it.