Also, if you need to test an area but don't want to move the player ribbon to it, you can click-drag from your own avatar to a map location. Then you can enter as a player while everyone else stays on the splash screen or main map page. You can drag your icon from the individual map back to the player ribbon to re-join the group. This is a trick that also works for 'splitting the party' between multiple areas. If you have issues with your players cheating by changing their character sheets when you're not around, get better players, or at least keep some notes on the GM Only section (hit points and ability scores, for example) of their sheets and be ready to punish them if you've made it clear that kind of behavior won't be tolerated. Another trick I have found helpful is make a macro for yourself that does /talktoyourself - then you can toggle it on and off when you need to test things you don't want to show up in the chat session.
