I agree with your shadows on none request. Invisible objects should be able to receive shadows---that is, to have shadows appear in the level at the invisible object's position and conformed to its shape. Just as a thought, you want to make sure that the shadows appear only on the object's faces that are facing the camera (since the object itself is invisible you might see through to the shadow on the other side of the object) because when you position the shadow in front of a sprite or panel you're going to want only the 'forward' shadow shape.


It would be awesome if parts from threads like that (rather than disappearing) made it to the WIKI as discussions of why certain features in the engine are the way they are and what they can be used for.