Extend SWF when rollover a button

I have a flash banner that has dropdown menus in it. One of the dropdowns is going to be very large, but I don’t want to make my swf tall enough to fit it, otherwise it will overlap the html page content below the banner. What I would like to do is to extend the swf/stage when i mouseover the button that displays the large dropdown list. How would I go about doing this? When I mouseout of the dropdown I would want to set the swf/stage height back to normal.