title: XMLHttpRequest in Firefox Extension
body: <p>I am writing a FireFox-Extension and want to load Data from Server. But when I try to initialize the XMLHttpRequest with:</p>
  
  <pre><code>var request = new XMLHttpRequest();
  </code></pre>
  
  <p>The error console says: </p>
  
  <pre><code>ReferenceError: XMLHttpRequest is not defined
  </code></pre>
  
  <p>Do I have to include something or why the XMLTttpRequest is not recognized?</p>