Child movieclip triggers ROLL_OVER in parent

This image shows the problem, the 3 is a PNG image with a nice drop shadow that expands quite far from the white square. It is a movieclip which was added by the square movieclip.

This obviously changes the size of the movieclip so the ROLL_OVER will trigger whenever the mouse is over either of these objects.

My question is, how would I make the movieclip “3” never trigger any sort of mouse event for its parent?

Things that do not work:
mouseEnabled = false; (why doesn’t this work?? ugh)
mouseChildren = false;
enabled = false;

Things I would prefer to not do:
make a separate invisible square movieclip