title: Sorting list Sencha Touch
body: <p>I have used the example code from "Intro to List Components". I was able to successfully run it on a android simulator. Now I want to sort it by firstName rather the lastName. When I changed to sorters: "lastName" to firstName, I can see that the Index bar is not in alphabetical order. How can I sort by firstName with proper index order?</p>
  
  <pre><code>Ext.regModel('Contact', {
  fields: ['firstName', 'lastName']
  });
  
  ListDemo.ListStore = new Ext.data.Store({
  model: 'Contact',
  sorters: 'firstName',
  
  getGroupString : function(record) {
      return record.get('lastName')[0];
  },
  data: [
      { firstName: "Domino",      lastName: "Derval" },
      { firstName: "Elektra",     lastName: "King" },
      { firstName: "Fiona",       lastName: "Volpe" },
      { firstName: "Holly",       lastName: "Goodhead" },
  
  
  ]
  });
  </code></pre>