I've just install Ubuntu 11.10 on virtual box. I've download Guest Additions. How to view this VM in second screen in full screen mode ? When Im opening full screen mode it's opening on 1 MAIN screen.
first show it in non-full screen mode. Drag this window to Your second screen. Then make it show in the full screen mode. Options choose from View menu.
It has to do with how your video in the host is set up... Whether you're using windows or linux as your host OS, it's probably the same problem.
In both cases, if your multiscreen setup has the OS thinking about them as separate displays, you can get seamless on one monitor to work. If the OS is thinking about it as one big display(as it can with xinerama and eyefinity groups) then when virtualbox asks how big the screen is and resizes itself...the OS is just doing what it's supposed to do.
If the host is linux, a good indicator is if they're all on one gnome cube side of if it's separate cubes. On the windows side, I don't know of a good indicator.