Comment 11 for bug 177510

I can reproduce this even with compiz turned off/not enabled. So this bug is not compiz-dependant.
Try to run a guest xp and use ctrl+alt+(right|left)to switch between workspaces.

Say, the virtualbox is running on desk2 (the only program on this desk or the one that's "focused"). If you are on desk1 and use the hotkey combination to switch to desk2 as long as you hold down ctrl+alt you can use the arrows to switch to desk3 or back to desk1. As soon as you release ctrl+alt on desk2 and the virtualbox gets focus the desktop switch hotkey stops working.

The problem is that the guest gets all the focus and virtualbox passes all the keystrokes to the guest (in this case windows xp) so that they don't "get through" to ubuntu. I've noticed this while running an program in guest xp which also had a ctrl+alt+arrows hotkey and responded to it.

Maybe a workaround could be that the virtualbox, apart of passing all the keystrokes to the guest, could echo these to ubuntu as well (or at least those specified in System>Preferences>keyboard shortcuts)? What do you think?