code: function(binding, event){
          if (this.checkModifiers(binding, event)) {
              var key = event.getKey(),
                  handler = binding.fn || binding.handler,
                  scope = binding.scope || this,
                  keyCode = binding.keyCode,
                  defaultEventAction = binding.defaultEventAction,
                  i,
                  len,
                  keydownEvent = new Ext.EventObjectImpl(event);
  
  
              for (i = 0, len = keyCode.length; i < len; ++i) {
                  if (key === keyCode[i]) {
                      if (handler.call(scope, key, event) !== true && defaultEventAction) {
                          keydownEvent[defaultEventAction]();
                      }
                      break;
                  }
              }
          }
      }
docs: Process a particular binding and fire the handler if necessary.
  @private
  @param {Object} binding The binding information
  @param {Ext.EventObject} event