title: In ExtJS, callParent() versus initConfig versus superclass
body: <p>what is the difference between these snippets?:</p>
  
  <pre><code>constructor: function(config) {
      this.initConfig(config);
  }
  
  constructor: function(config) {
      this.callParent(arguments);
  }
  
  constructor: function(config) {
      this.superclass.constructor.call(this, config);
  }
  </code></pre>
  
  <p>AND, how does it differ to be overriding OTHER methods than <code>constructor</code>?</p>