I've played other games where thieves can't hide while holding a light and I think it makes sense. I know that bringing realism into a fantasy game setting is always risky business, but I think it makes sense here.
Just as the description help thread says no 7 foot tall halflings, I think we should say no to hiding while holding a lantern.
My idea: Give thieves/ninjas infravision spell (or skill with a cooler sounding name?) and don't let them hide while holding lights.
