ondrejd's blog

As I worked on tbNotes extension I needed to add item to the message header view (see the picture).

I didn’t found any usefull informations on MDC or Google so I look into the Thunderbird‘s sources (msgHdrViewOverlay.js) file and there I founded it. Solution is simple:
Code placed in overlays.xul:

  <!-- Message header view overlay -->
  <rows id="expandedHeader2Rows">
    <row align="center">
      <label class="headerName" value="&headerNotes.label;"/>
      <hbox id="tbn-notesmsgheaderviewpane-hbox"/>
    </row>
  </rows>

and needed JavaScript:

  // Listener for gMessageListeners (msgHdrViewOverlay.js)
  extensions.tbnotes.messageListener = {
    onStartHeaders: function() {
      // Code where I'm updating [hbox#tbn-notesmsgheaderviewpane-hbox] ...
    },
    onBeforeShowHeaderPane: function() {},
    onEndHeaders: function() {},
    onEndAttachements: function() {}
  };
  // ...
  // Register listener 
  if(typeof(gMessageListeners) != "undefined") {
    gMessageListeners.push(extensions.tbnotes.messageListener);
  }

Don’t remember that lister should implement all methods mentioned above or will be thrown errors from msgHdrViewOverlay.js.