I noticed while checking the settings of my Whonix-Gateway that the Shared Clipboard is enabled, and set to "Host To Guest". I felt that this was insecure, and disabled it.
I might just be paranoid, but I don't like the idea of my copy-paste buffer being accessible to the VM. I would rather it be disabled by default with instructions made available on enabling it - and only when necessary. I know that is exactly the policy already for Whonix-Workstation, but I think it should be the case for both systems.