You're right, pictures might help ... we just bought the place so here's a picture from the listing. It's not the best quality, but it gives a good idea of what I'm trying to do. The screen will need to hang in front of the arched opening (there's a stair case in behind it, going down). Closing the opening off with drywall is unfortunately a no no. Also that arch has a small sil (sort of like a windows sil) so the screen will have to stick away from the wall, hence why I was thinking of hanging it from the ceiling. Although technically it could be hung from the wall if I can make sure it's a few inches away from it.