You can draw an image/background ctrl behind the GraalControl to create a "background" image easily.
Also, you could have a tiles for background and lay the actual walkable tiles on layer 1 and have the bg tiles on layer 0. Since all layer 1 tiles would be blocking, and all layer 0 tiles would not need to be itd be simple as all get up
plus would be easy to test if you are on a special bg thing by just testing the tile
Anyways, tile layers are your best bet here.. if you have a layer editor. Not to mention mine isnt even 100% done because Stefan keeps messing up gmap layers
