How does the pop-up window trick work?
When you click a link labeled “visualize the structure,” you are calling a javascript function which launches a new window (if javascript is enabled on your browser). We got this trick from http://www.edginet.org/techie/website/javascript.html#POP . If you don’t have javascript enabled, then we invoke the concept of Graceful Degradation. In this case, your broswer just goes to the pop-up page while remaining in the current window.
