title: Thunderbird compose-send-message event does not fire
body: <p>I have followed <a href="https://developer.mozilla.org/en/Extensions/Thunderbird" rel="nofollow">the tutorial</a> for getting a Thunderbird extention going and succeeded in getting extensions that use the "load" event to work (the basic "date" example and random text using <code>alert("hey");</code> both work).</p>
  
  <p>However, I can't seem to get any message-based events to trigger.  I've tried using various types of alerts and it just seems my code is not being ran.  For example:</p>
  
  <pre><code>function send_event_handler( evt ) {
    alert("hohoho");
  }
  
  window.addEventListener( "compose-send-message", send_event_handler, true );
  </code></pre>
  
  <p>How do I get events to trigger that allow me to modify message bodies?</p>
  
  <p>My test platform is using Thunderbird 13.</p>
  
  <p>My manifest is:</p>
  
  <pre><code>content     thundersafe    chrome/content/
  overlay chrome://messenger/content/messenger.xul chrome://thundersafe/content/thundersafe.xul
  </code></pre>