title: Firefox extension - Display customized popup message just above the status bar
body: <p>I am new to extension development, I have a requirement wherein I need to do some checking on the page and display a popup message at the bottom of main window, just above the status bar. </p>
  
  <p>I used the insertAfter attribute with value "browser-bottombox" but this does not display the label at all.</p>
  
  <pre><code>&lt;overlay id="gHook" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"&gt;
     &lt;hbox insertAfter="appcontent" height="75" id="glhbox"&gt;
        &lt;label value="Sup Message"&gt;&lt;/label&gt;
     &lt;/hbox&gt; 
  &lt;/overlay&gt;
  </code></pre>
  
  <p>This does not display any thing.</p>
  
  <p>Help much appreciated. Thanks</p>