Stretching part of a movie clip

A few days ago, I visited a Flash site (sorry, I can’t remember what it is) and was very curious as to how it was made. At the bottom of the swf was a navigation bar that stretched from the left end of the browser to the right. The links on the navigation bar were all on the left side, and the right side was just an extension of the bar’s pattern. The part I’m curious about is how the bar stretched to the other end of the screen without resizing the text or images of the rest of the swf. Now that I think of it, I suppose the swf could have just had a very wide stage size and part of it went off the screen - I can’t remember if I could have scrolled or not. But either way…would it be possible to create an SWF that changes the width of a movieclip so that it stretches to the width of the screen, without stretching any other aspect of the swf? Thanks.