Buttons and rollover.
I think the choice of any object is a button is not right, output is possible not a bad idea, but I think the user should be able to decide what is and is not a button. And being able to modify their behavior more complex.
In states of object, rollover state should be able to put more objects, will remove then, including images, do scale, do change opacity... Right, now there is very little chance to act on a button.