Fixed object size on resizable stage

I have a SWF stage that needs to be resizable, as it loads content dynamically which may have different dimensions. Yet, I need an object (namely a 'Close' button) to keep its absolute size no matter how big or small the stage gets. Is there any way to achieve this?

I also need it to keep its relative position, let's say always at the top right corner of the resized Stage :/