title: Inheritance of Delegate
body: <p>I created a Class with a Selectbox and some Listitems. To change the Label of these Items I set the Delegate of the selectbox controller with a <code>configureItem</code>.</p>
  
  <p>Know I want to add some Child Elements of these class and add some Items to the list. Now I have to adjust the <code>configureItem</code> by calling a function in the configureItem. This Function checks if the Item is in the current class, when it is not I call the superclass method who handles the label of his Items.</p>
  
  <p>This worked well is Qooxdoo 5.0.2. Now I changed to Qooxdoo 6 to use the new compiler and I get the Error: <code>Uncaught TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them</code> when calling the Superclass Method.</p>
  
  <p>Here are some Code snippets:</p>
  
  <pre class="lang-js prettyprint-override"><code>//Set Delegate in superclass
  this.operatorController.setDelegate({
      configureItem : function(item) {
          that.operatorDelegateItems(item, that);
      }
  });
  
  // Superclass Method
  operatorDelegateItems : function(item, that) {
          switch (item.getLabel()) {
          case "":
              item.setLabel(qx.locale.Manager.tr("Ist Vorhanden"));
              break;
          case "-":
              item.setLabel(qx.locale.Manager.tr("Ist nicht Vorhanden"));
              break;
          case "Nachfolger":
              item.setLabel(qx.locale.Manager.tr("Zeige Nachfolger"));
              break;
          }
      }
  
  // Child class Delegate FUnction
  operatorDelegateItems : function(item, that) {
      if (item.getLabel() == "Period")
          item.setLabel("Jahresintervall");
      else
          that.base(arguments, item);
  }
  </code></pre>
  
  <p>Someone can help me with this or is there a better approach to solve my problem?</p>