function showpanel(){
    document.getElementById("nav").style.visibility="visible";
}

function closepanel(){
    document.getElementById("nav").style.visibility="hidden";
}

function showmenu(num){
    if(num!=0){
        showpanel();
        for(var i=1;i<7;i++){
            document.getElementById("menu_"+i).style.display="none";
        }
        document.getElementById("menu_"+num).style.display="block";
    }
}

if(!!window.find){ 
    HTMLElement.prototype.contains = function(B){ 
        return this.compareDocumentPosition(B) - 19 > 0 
    }
}

function closemenu(obj,event){
    var obj1=document.getElementById("daohang");
    var count=0;
    if (event){
        var browser=navigator.userAgent;
        if (browser.indexOf("Firefox")>0){
            if (obj1.contains(event.relatedTarget)) { //如果是子元素
                count=1;
            }
        }
        if (browser.indexOf("MSIE")>0){
            obj1=document.getElementById("dingwei");
            if (obj1.contains(event.toElement)) { //如果是子元素
                count=1;
            }
        }
    }
    if(count==0){
        closepanel();
    }
}