code: function(event){  
                      if (event.data == config.channel + "-ready") {
                          // replace the eventlistener
                          callerWindow = ("postMessage" in frame.contentWindow) ? frame.contentWindow : frame.contentWindow.document;
                          un(window, "message", waitForReady);
                          on(window, "message", _window_onMessage);
                          setTimeout(function(){
                              pub.up.callback(true);
                          }, 0);
                      }
                  }
docs: add the event handler for listening