Creating an Over or Down State
Select how to create the state: copy from an existing state or draw your own.
A maximum of one shape can reside in a button state. If you want to include more than one shape or have the state be animated, select "I will draw my own" and then select Shapes > Add Movie Clip. Inside the movie clip, you can have multiple shapes and frames.
Selections may be disabled if a shape already exists. Select the current shape and delete it.
Definition of Terms
The Over state is how the button appears when the button is over the mouse.
The Down state is how the button appears when the mouse presses the button.
So there can be up to three shapes associated with a button, one for each state.