title: Javascript AddEventListener is undefined
body: <p>try to make it work in firefox, but get: undefined</p>
  
  <pre><code>XMLDocument = new XMLHttpRequest();
  
  function startSlides() {
  ...
  XMLDocument.addEventListener('click', processEvent, false);
  }
  
  function processEvent() {
  //...
  }
  </code></pre>