So far, the only other key I have found to not be sent to the Windows host is the WINDOWS key and its combinations, such as WIN+E (Open Explorer), WIN+D (Show Desktop), WIN+M (Minimize All Windows). The WIN-key triggers the openSuse Program Menu. (This is not terrible, just unexpected, and wouldn't necessarily require fixing, as far as I'm concerned. One could consider it a feature since pressing WIN gets us back to the remote guest straight away.)