any code you use in your button class will effect all buttons
you create. so, if you wanted some buttons to do one thing (move
bigsquare to the right) and some to do another (move it to the
left), you would need to change your class and pass a parameter
when you instantiate a button that would indicate whether it's a
left-move or right-mover. you would then attach the appropriate
listener to the button.
or you could add listener code in your fla to your button
instances, though this would undermine your oop efforts.