or you could make the bouncing balls effect - (on the example browser)
so that the sprite randomly moves bouncing off invisible solids.
and if you dont want it to keep spawning in the smae place:
on start of layout-set sprite x,y to random(whatever you boundreis of your upper portion of the screen is)
you should know for i in range right?
tell me if this works if not ill show some exmpls
happy to help,
Radkampfwagen