backgroundSwap.py https://gist.github.com/cclauss/7132028
Create three background images in scene.setup() then in scene.draw() use the x coordinate of the user's drag location to determine which background image to display. The grey dot represents foreground drawing that takes place on top of one of three different backgrounds. This method could be used for example to make a multilevel game where the graphics for each level were drawn up front and stored in PIL images. The foreground would then be drawn on top of the background of the current level in the scene.draw() method.