Today I spent some time to get Ubuntu 12.10 installed as a virtual machine using VirtualBox. That as such wasn’t the challenge. For example a pretty good description can be found at Windows Seven Forums.
Getting the guest additions installed was the problem. Quite a few sources suggested to use VirtualBox’s menu “Devices” – “Install Guest Additions…” However, what was offered as a solution didn’t work in my case. Note that I’m not a Linux or VirtualBox expert, so my lack of knowledge might have been the reason.
After quite some search I found a very good description on Sysprobs. Dinesh did a fantastic job with his blog post. Now I can resize the VM’s window any way I like and the VM’s screen adjusts properly. Almost seamless integration Nice!