Mouse to edges (i.e. VirtualBox Fluid mode)

[dabicho <tsukebumi gmail com>]

Hi.
I have a problem, in this particular case with VirtualBox , but I
guess it is general.

With VirtualBox in full screen or fluid mode, I should be able to move
my mouse cursor to the lower edge of the screen and have a menu
appear. This is not posible now with gnome 3 (3.2)
Without this, I have to switch back and forth between modes for some tasks.

Is there anythin I am missing?

Thank you.