maybe..
How about having the address bar be partially hidden and slide out when you click/drag it? Maybe just 5-10px showing?
That way it doesn't disappear completely when you scroll and can't be replaced in the same manner as this case. I guess maybe a click/drag event handler in the top few px could catch any 'near misses' if your aim isn't too good, but then you would still have this bar at the top of the screen that would be realtively obvious to all but those who are having a careless moment or are in a rush etc.