I have an Ubuntu 11.10 guest running within VirtualBox, on a Windows 7 host. I have the 3D acceleration option selected for the guest and I am able to access Unity 3D and Compiz. I find the whole experience of developing with the guest OS very productive. :)
When running Ubuntu normally, not as a guest, i.e. in a dual boot arrangement, I would use an application like Shutter to grab screen shots for documentation etc. However, after moving to a virtualised environment, when I try and capture from Shutter the entire screen just blacks out -- I am running Ubuntu guest fullscreen. When I then try to make some kind of selection anyway (blind to the actual content I am selecting of course), I just get a blank white image.
I am not surprised that I am having such difficulties. I guess it is due to how Shutter is accessing the pixel content of the desktop via either the Xorg stack, or through some interface to the working memory of the graphics card; there just must be a difference when running in a VM vs natively, but my knowledge bottoms out here :(
I tried using the GNOME screen shot utility and it seems to suffer from the same problem; I could have lived with it's limited feature set if it had worked. Then I tried enabling the ScreenShot plugin from CompizConfig Settings Manager and hey presto I got images (they are saved on the desktop), but the power of this facility of Compiz -- holding the Windows key and drag-selecting an arbitrary region of the screen -- is painfully limited compared to the feature set offered by Shutter.
Even if a solution for Shutter is not forthcoming, some insight into how the screen capture tool interfaces to the Xorg or GPU driver that can shed some light on this would be great. A specific solution for use with Shutter would be champion!