title: How can I make the modal popup scroll its contents with the page?
body: <p>I've got a modal popup and when it loads contents that are taller than the browser height I am unable to scroll down to view the rest of the information.  Instead the background can scroll but the popup won't.</p>
  
  <p>Instead I'd like to have the popup stay put and when the user scrolls up or down it leave the popup in place and let them scroll to the bottom of the contents.  If you make a super long post on Facebook the popup works correctly and I'd like to know how I can get this same effect with this control.</p>