Comment 25 for bug 971018

This isn't really a bug in Unity. If you turn off mouse pointer integration (under the "Machine" menu) to prevent the host from stealing the focus everything works like a charm. This means that with pointer integration enabled and auto hide turned on when the mouse reaches the edge of the screen Vbox/VMWare decide to give focus to the host, not the guest. There isn't really much Unity can do about that.

As a workaround you can use: Don't hide the launcher, disable mouse pointer integration, use <super> to access the launcher, or <alt>+<f1>.