The Undocumented SWF Tag

If your working with Flex Builder 2 and trying to set the default swf size for the project there are two ways to do it.

1) Use the Swf Tag

[SWF(width="800", height="600")]
public class Carousel extends Sprite

2) Goto the Actionscript compiler options and you can add optional params for the mxmlc
compiler there.