title: Gmail extension/gadget API - how to add a button to the compose toolbar?
body: <p>I'm trying to figure out how can I add a button to the Gmail compose window. </p>
  
  <p>In "Gmail Labs" they have some extensions that add certain buttons For example "Send &amp; Archive" button and "Inserting images" button, so I assume this is possible.</p>
  
  <p>I checked their API <a href="http://code.google.com/apis/gmail/docs/">here</a> and it seems that you can either add a gadget to left sidebar or use contextual gadgets that are dependent on the message context. I'm looking for a way to add a button to the toolbar of the compose window, and both options don't seem to support it.</p>
  
  <p>Do you know how can this be done? </p>
  
  <p>If it's not possible using Gmail API, is there another way I can achieve this? Maybe by creating a Google Chrome extension or user scripts? </p>
  
  <p>I would appreciate any info that can direct me in the right direction.</p>
  
  <p>Thanks.</p>