Must there always be four icon panels and are they fixed in place by the OS?
If the answer to both is "yes". then could one take "slices" of the background graphic in an image-editing program, save the parts that would normally be hidden by the panels and use them as the panel graphics?
Inelegant, I know, but it would at least give the impression of the icons floating over the BG. (Hey... I'm not a coder; I'm just the Graphics Geek!)