Fix bug of images always staying on top of something
If an image is used as background for areas (so you put stickies on top of the image) it happens that the image is "always on top" (stickies fall behind it), when the image is not recognised as part of the area (e.g. it is bigger, or you have different areas on the image.
This makes it very hard to combine areas and images. Stickies should per default be on top of images (I cannot think of a use case we would want the to be covered, unless we want to cover the area which is already a built-in function in the area outline). Who still wants stickies underneath could just set these as "send to back"?