A button on the map to completely disable fog of war for that map.
Right now by default when a token reveals a piece of a map and moves away from it, that piece of the map stays revealed for them while obscured. We have the option to manually reset the Fog of War view for some tokens by right clicking them.
I propose an option that no fog of war is saved and that a token can only see what they are looking at that very moment. Great for some dungeon crawling where you require the players to remember their way back.