导航菜单点击后，怎么保存点击后的样式？
我的意思就是：在点击左边树导航菜单时，菜单就会变为灰色，右边 会打开新的页面，当鼠标点击新页面时，菜单的灰色样式就消失了，变为之前的样式，这个问题怎么解决那，求高手，小弟 很着急，谢谢啦！
这是我的 menu.jsp :
<script language="javascript">
iniTtree();
</script>
<script language="javascript">
<!--
var openID = ""; //处于展开状态的菜单ID
var firstLength = 3; //一级子菜单的长度
var subLength = 3; //两级菜单的长度差

var off_img = "<%=request.getContextPath()%>/images/collapse.gif";//缩进时图片
var on_img = "<%=request.getContextPath()%>/images/expand.gif";//展开时图片

function tdclick(urlname) {
form1.action = urlname;
form1.target = "mainFrame";

//去掉所有没选中的tr为
var rows = document.getElementsByTagName("tr");
for ( var i = 0; i < rows.length; i++) {
rows[i].className = "";
}
//设置选中的tr
event.srcElement.parentNode.className = "red";

form1.submit();
}

function tree(ctlID) //点击菜单时菜单的伸缩
{
var isOpen = -1; //该菜单下的所有菜单是展开还是缩进 0为缩进,1为展开
var obj;
for ( var i = 0; i < document.all.length; i++) {
obj = document.all.item(i);
if (obj.id.length > firstLength) {
if (obj.id.substring(0, ctlID.length) == ctlID
&& obj.id.length == (ctlID.length + subLength)) {

if (obj.style.display == "none") {
obj.style.display = "";
} else {
obj.style.display = "none";
}
} else { //所有下级菜单都缩进
obj.style.display = "none";
changeImage(obj, off_img);
}
}
}
}

function tree1(ctlID) //二级子菜单
{

var isOpen = -1; //该菜单下的所有菜单是展开还是缩进 0为缩进,1为展开
var obj;

for ( var i = 0; i < document.all.length; i++) {
obj = document.all.item(i);
if (obj.id.length > firstLength) {
if (obj.id.substring(0, ctlID.length) == ctlID
&& obj.id.length > ctlID.length) {

if (obj.style.display == "none") {

obj.style.display = "";
changeImage(document.all(ctlID), on_img);

} else {

obj.style.display = "none";
changeImage(document.all(ctlID), off_img);

}

} else if (obj.id.substring(0, ctlID.length) != ctlID) {//所有同级菜单都收缩
if (obj.id.length == ctlID.length) {

changeImage(obj, off_img);

} else if (obj.id.length > ctlID.length) {

obj.style.display = "none";

}
}
}
}
}

function iniTtree() {
var thisID = "";
for ( var i = 0; i < document.all.length; i++) {
if (document.all.item(i).id.length > 0) {
if (thisID == "")
thisID = document.all.item(i).id;
if (document.all.item(i).id.length > thisID.length)
document.all.item(i).style.display = "none";
}
}
tree(thisID);
}

//把oTr里的图片换成sImg
function changeImage(oTr, sImg) {
//var oTr = event.srcElement.parentElement;
if (oTr.tagName != "TR")
return (false);

var aObj = oTr.getElementsByTagName("IMG");
for ( var i = 0; i < aObj.length; i++) {
if (aObj[i].src != null
&& (aObj[i].src.indexOf(on_img.substring(on_img
.indexOf("/"), on_img.length - 1)) != -1 || aObj[i].src
.indexOf(off_img.substring(off_img.indexOf("/"),
off_img.length - 1)) != -1)) {
aObj[i].src = sImg;
}
}
}

//选中的颜色
function selectThis(obj) {

var obj1 = obj.parent.paren