[DeliMIter]

Вроде как перед тем, как задавать вопрос, стоит хотя бы прочитать статью хелпа по теме, а не только узреть [read-write] в заголовке.

When the value of the scaleMode property is set to StageScaleMode.NO_SCALE, the stageWidth property represents the width of Flash Player. This means that the stageWidth property varies as you resize the Flash Player window. When the value of the scaleMode property is not set to StageScaleMode.NO_SCALE, the stageWidth property represents the width of the SWF file as set during authoring in the Document Properties dialog box. This means that the value of the stageWidth property stays constant as you resize the Flash Player window. This property cannot be set.