Pop-up blocker detection script

Does anyone know how to detect pop-up blockers?

I just visited a site that has a very nice way of detecting if the client’s browser has pop-ups blocked.


It presents the visitor with an alternative page with a message that informs the user about the pop-up blocker and gives them a link back to the home page. I think the alternative page is http://www.bobbretttennis.com/bye.html.