title: Uncaught TypeError: Cannot read property 'apply' of undefined with Sencha
body: <p>I have some problems with sencha touch.
  I have this simple code :</p>
  
  <pre><code>items: [
          {
              name: "horo",
              xtype: 'togglefield',
              label: 'Horodateur ?',
              labelWidth: '55%',
              disabled: false,
              listeners: {
                  beforechange: function (slider, thumb, newValue, oldValue) {
                      if (oldValue == 0 &amp;&amp; newValue == 1) {
                          alert("toto");
                      }
                  },
                  change: function (slider, thumb, newValue, oldValue) {
                      if (oldValue == 0 &amp;&amp; newValue == 1) {
                          alert("titi");
                      }
                      else if (oldValue == 1 &amp;&amp; newValue == 0)
                          alert("tata");
                  }
              }
          },
  </code></pre>
  
  <p>And I have this error on my console : </p>
  
  <blockquote>
    <p>Uncaught TypeError: Cannot read property 'apply' of undefined.</p>
  </blockquote>
  
  <p>What's the problem ?
  My console say something else, maybe the <code>Controller.js</code> is the problem.</p>