title: How to have AJAX trigger the browser's loading indicator
body: <p>I'm making an ajax-enabled lab scheduling program, and some of the ajax operations aren't exactly quick. </p>
  
  <p>In Gmail, when you go to your inbox, send a message, etc. the browser acts like it's loading (In FF the stop button becomes enabled, the progress bar appears), but it's not on a new page, it's done via AJAX. </p>
  
  <p>How do they do this? I have a little spinny indicator, but it would be a nice touch to have the browser act like it's loading. Any ideas?</p>