With DisplayFusion 7, if VirtualBox was full screen it could grab the windows key press and handle it but with the upgrade to DisplayFusion 8 pressing the windows key causes it to be handled by the host OS (Windows 8.1 in this case).

Is there a way to disable this new, more aggressive windows key handling?

Thanks Keith. Just to verify, I downgraded to 7.3.4 and VritualBox is able to handle the windows key again when running full screen.