Does the maptool support (or plan to support) the ability for the GM client to add visibility masks for clients? The GM might have a large dungeon pre-built, but only want to show the players the areas that their characters have explored so far. Something akin to "fog of war" in many RTS games.
The current release does not support fog of war yet. However, there is already a tracker for it:
It should make it in the code base in the next couple releases
Just as an update version 1.0M5 has fog of war in it. This version will be released as Beta later this week but is available now from the Alpha section on our website.