title: Sencha touch 2 Event listeners in Ext.Define
body: <p>I was reading the sencha docs about Event handling and the listeners config. 
  In the documentation of <a href="http://docs.sencha.com/touch/2.2.0/#!/api/Ext.dataview.List-cfg-listeners" rel="nofollow">the listener config</a> I found this note : </p>
  
  <blockquote>
    <p>Note: It is bad practice to specify a listener's config when you are defining a class using Ext.define(). Instead, only specify listeners when you are instantiating your class with Ext.create().</p>
  </blockquote>
  
  <p>I have seen a number of S.O. answers which have <strong>listeners</strong> in the <code>Ext.define()</code>. </p>
  
  <p>Also I came accross this blog post about <a href="https://web.archive.org/web/20120517040029/http://mitchellsimoens.com/2011/12/ext-js-4/ext-define-and-listeners-as-a-property-bad/" rel="nofollow">the evils of Ext.define and listeners</a> but i think this is <em>more relevant</em> to Ext-Js than to Sencha Touch 2. And I am fairly new to Sencha Touch.</p>
  
  <p>Can anyone explain the difference cons of adding listeners in the Ext.define() and what difference does it make?</p>