If you open the permissions dialogue of a fence gate and then bash it down (perhaps even a house door?), it will reappear for clients in range after using the dialogue (enter a (new) name, and click apply changes). The gate will reappear in the clients in range, won't open, and will be impassable, and has no further options in the context menu to interact with it because it doesn't exist server side assumably. The gate does not appear after relogging of course. I guess it could be exploited to create an impassable barrier until clients in range relog.