为什么openWindow在PC端采用parent跳，这样iframe超过2层会有问题吧

$.openWindow = function(url, id, options) {  
        if (typeof url === 'object') {  
            options = url;  
            url = options.url;  
            id = options.id || url;  
        } else {  
            if (typeof id === 'object') {  
                options = id;  
                id = url;  
            } else {  
                id = id || url;  
            }  
        }  
        if (!$.os.plus) {  
            //TODO 先临时这么处理：手机上顶层跳，PC上parent跳  
            ***if ($.os.ios || $.os.android) {  
                window.top.location.href = url;  
            } else {  
                window.parent.location.href = url;  
            }***  
            return;  
        }  
        if (!window.plus) {  
            return;  
        }  
                ..................  
};