I was able to solve this issue by setting the "No Focus" rule in Compiz window rules for VirtualBox OSE
1. Open Compizconfig-settings-manager
2. Open "Window Rules"
3. Put "title=VirtualBox OSE$" (without quotes) into the No Focus rule
Unfortunately this will disable VirtualBox shortcut keys
I was able to solve this issue by setting the "No Focus" rule in Compiz window rules for VirtualBox OSE settings- manager
1. Open Compizconfig-
2. Open "Window Rules"
3. Put "title=VirtualBox OSE$" (without quotes) into the No Focus rule
Unfortunately this will disable VirtualBox shortcut keys