title: How does it display designate folder in Google Picker for Google Drive file?
body: <p>I use the Google Picker API, and below is my code:</p>
  
  <pre><code>var picker = new google.picker.PickerBuilder().
              addView(new google.picker.DocsView()).
              setOAuthToken(oauthToken).
              setDeveloperKey(developerKey).
              setCallback(pickerCallback).
              build();
              picker.setVisible(true);
  </code></pre>
  
  <p>I want it to display designate folder initially and only shows the files and folders beneath it, how should I modify? Thanks!</p>