Flash MX 2004.
element.height
Property; a float value that specifies the height of the element in pixels. Do not use this property to resize a text field. Instead, select the text field and use document.setTextRectangle(). Using this property with a text field scales the text.
The following example sets the height of the specified element to 100:
fl.getDocumentDOM().getTimeline().layers[0].frames[0].elements[0].height = 100;