title: Private members when extending a class using ExtJS
body: <p>I have done some research on the <em>ExtJS forum</em> regarding <strong>private methods and fields</strong> inside a <strong><em>extended class</em></strong>, and I couldn't find any real answer to this.</p>
  
  <p>And when I say an <strong>extended class</strong> I mean something like this:</p>
  
  <pre><code>Ext.ux.MyExtendedClass = Ext.extend(Ext.util.Observable, {
      publicVar1: 'Variable visible from outside this class',
      constructor: function(config) { this.addEvents("fired"); this.listeners = config.listeners; }, // to show that I need to use the base class
      publicMethod1: function() { return 'Method which can be called form everywhere'; },
      publicMethod2: function() { return this.publicMethod1() + ' and ' + this.publicVar1; } // to show how to access the members from inside another member
  });
  </code></pre>
  
  <p>The problem here is that everything is public. So, how do I add a new variable o method within the scope of <strong>MyExtendedClass</strong> that cannot be accessed from outside but can be access by the public methods?</p>