dimensions of loaded swf's stage

Question

Here's the situation - I've got a shell that loads an external .swf. Now, that .swf is 800x600, but it's an animation piece, and there are elements that extends off the stage. When I load the .swf into the shell and call its width attribute, it returns 1200 - because it's including the elements that break out of the stage.

This isn't what I want - ideally, there would be two properties, one to return the 'calculated width' and one to return the 'default width'. Do these properties exist, and if not, what's the best workaround?