Virtual Box and Fedora 12 Guest

Installing Guest Additions on Virtualbox enables you to use some very powerful  features such as seamless integration and full screen resolution mode.

for a fresh fedora 12 install

1. su -
2. yum –y install dkms gcc kernel-devel kernel-headers
3. reboot
4. cd /media/VBOXADDITIONS_3.1.4_57640 (version 3.1.4)
5. ./VBoxLinuxAdditions-x86.run (for 32bit)
6. reboot
7. done!

for more detail

http://digitizor.com/2009/05/26/how-to-install-virtualbox-guest-additions-for-a-linux-guest/

and..

Fedora 12 Installation and Post-Installation Guide

http://www.my-guides.net/en/content/view/174/26/