cc.eventManager.addListener({             event: cc.EventListener.KEYBOARD,             onKeyReleased: function(keyCode, event) {                 if (keyCode == cc.KEY.back) {    //beta版本这里的back的keycode有误，也可以自行改为6                     cc.log("return button clicked. keycode:" + keyCode);                     cc.director.end();                 }                 else if (keyCode == cc.KEY.menu) {    //beta版本这里的menu的keycode有误，也可以自行改为15                     cc.log("menu button clicked. keycode:" + keyCode);                 }             }}, this);        //进入后台         cc.eventManager.addCustomListener(cc.game.EVENT_HIDE, function(){             //         });        //恢复显示         cc.eventManager.addCustomListener(cc.game.EVENT_SHOW, function(){             //         });