title: Detect when an iframe starts to load new URL
body: <p>How can I detect that an iframe on my page <strong>starts</strong> to load a new page?</p>
  
  <p>Our situation is:</p>
  
  <ul>
  <li>When iFrame content starts to change we need to display a "loading" animation and hide the search-box.</li>
  <li>I know how to handle the "iframe has finished to load" event (to hide the animation) but not how to catch the initial "starting to change" event...</li>
  </ul>
  
  <p>Note:
  I can attach jquery "click" hook to the links on the menu, which will work. However, inside the iframe content there are many cross-reference links, and the "change" event also applies for them! So we need to catch event when <strong>user clicks on a link inside the iframe</strong> or when the <strong>iframe src is changed via javascript</strong> - because we also want to show the loading-animation and hide the search-box.</p>