title: How do I add an image icon for custom button in outlook
body: <p>I have a custom button in outlook and I have to add image icon for the same button.</p>
  
  <p>Ribbon XML is:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;button id="GoToAppConfiguration" 
      label="Application Configuration" 
      getImage="GetCustomImage" 
      onAction="GoToAppConfigurationClicked" 
      size="normal" /&gt;
  </code></pre>
  
  <p>I want to  write ribbon callback method but how do I write the same and how do I use an image stored in a Resource folder under the Addin project.</p>