Turn iframe (external src) into a window?

[Frank C]

My site hosts a iframe whose initial src is an external website. I'd
like to be able to allow users to click a button and "pop out" that
iframe into its own window. I can of course just call window.open and
pass the initial src url... but if the user has navigated in the
iframe... I want the page he's currently on to show up in the new
window.

Whats the best way to do that ?

I've tried

location.href = iframeObj.contentWindow.location.href

But of course that doesn't seem to work due to browser security,
right?

Thanks,
frank