I was just playing around with this and I think something has changed in a recent beta build perhaps.
Image offsets no longer work as before, whereby you could define offsets for an individual state. Now, if I apply an image offset to the "Mouse away" state, it effects all states. In addition, image offsets appear to have no effect on an object that is grouped with another object. This basically makes image offsets somewhat pointless
And, as stated by the OP, altering the sharpness or offsets of a shadow for a particular state gives the object itself an offset for that state - this is definitely not how this used to work.
I suspect (hope) that this is just a bug and that we can get the old behaviour back for these parameters.
*edit* above applies to objects that are not contained children, as other posters may have been referring to - however it seems a bit counter-intuitive to have 2 sets of behaviours for these parameters depending on their parent-child relationships