I've been looking for a cheap whiteboard and I realized I have a window right next to my desk that ought to work fine. It occurs to me though, that dry erase markers may "burn" into the glass especially in direct sunlight. I have a tendency to write on a whiteboard and then leave it for a while. Would this leave marks on the window even after I erased? If so could they be easily cleaned off using a window cleaner? Or should I avoid using the window as a dry erase board?