I just made a main map (ground) as the "map layer". Then I put two "Token" layer objects on top of each other: Let's call them "Building" and "Roof". Both are on the token layer but "IsDrawing" is enabled for both. This makes it easy to access when on the token layer and doesnt conflict with the map itself for what's next: When a player walks in you can R-click on the roof and click "To Back". When they leave R-click on the Building token and click "To Back" again and the roof appears on top again. Both token/drawings would have to be the same size, of course. Sure it isnt "automated" for when a PC walks in, but that probably happens infrequently enough that this workflow hopefully suffices. For more realism you could also make the "Building" enclosed outside of light so only the player that enters "sees" it. I don't know of a way to make some tokens only seeable by some characters.. (So only the character that entered see the roof removed where the other players only see the roof). A quick search on the forums and features didn't yield the ability to do this. That would be cool though so that, for example, players with stealth could see their own token but other players couldn't see it.