I was going to leave a big bad guy on the GM layer since he is invisible at the start of the encounter. Then I thought I better test what happens in the players view when I start using the measuring tool while I'm on the GM layer. The players see the GM doing measuring. Which would give the bad guy's position away. So I thought it might be nice to have a way to not let the players see when the GM is measuring things and other times he might want them to see when he is measuring. Easiest solution is when the GM is on the GM Layer don't let the players see anything he does. But there might be times when the GM isn't on the GM layer and he still doesn't want the players to see what he does? Maybe need a better solution, but anyway they do it I think it would be very useful for when you are checking out ranges, etc.