title: Firefox extension icon on the navigation bar using the Add-on builder
body: <p>How do I add an icon to Firefox that opens up a panel on click on the navigation bar. An example is the Firebug extension. The only thing that will be different, is that I want a panel to appear.</p>
  <p><a href="https://i.stack.imgur.com/hpagb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hpagb.png" alt="Firebug Icon" /></a></p>
  
  <p>Thanks!</p>