title: How to get index of selected Ext.form.field.PickerView item?
body: <p>How I can to get index of selected Ext.form.field.PickerView item?
  I am trying to use it:</p>
  
  <pre><code>Ext.define('Bind.CL.FormD.view.MyCombo', {
      extend: 'Ext.form.field.Picker',
  alias: 'widget.mycombo',
  
  ...something code...
  
  this.on('expand', function () {
              var combo = Ext.ComponentQuery.query('mycombo')[0];
              var value = combo.getValue(); //or getRawValue();
          }, this);
  </code></pre>
  
  <p>But it doesn't work..</p>