Помогите разобраться с меню-аккордеоном

http://onlyminecraft.ru/

<script type="text/javascript">   
   // <![CDATA[   
   var myMenu;   
   window.onload = function() {   
   myMenu = new SDMenu("my_menu");   
   myMenu.init();   
   };   
   // ]]>   
   </script>

function SDMenu(id) {
   if (!document.getElementById || !document.getElementsByTagName)
    return false;
   this.menu = document.getElementById(id);
   this.submenus = this.menu.getElementsByTagName("div");
   this.remember = true;
   this.speed = 5;
   this.markCurrent = true;
   this.oneSmOnly = false;
}
SDMenu.prototype.init = function() {
   var mainInstance = this;
   for (var i = 0; i < this.submenus.length; i++)
    this.submenus[i].getElementsByTagName("span")[0].onclick = function() {
     mainInstance.toggleMenu(this.parentNode);
    };
   if (this.markCurrent) {
    var links = this.menu.getElementsByTagName("a");
    for (var i = 0; i < links.length; i++)
     if (links[i].href == document.location.href) {
      links[i].className = "current";
      break;
     }
   }
   if (this.remember) {
    var regex = new RegExp("sdmenu_" + encodeURIComponent(this.menu.id) + "=([01]+)");
    var match = regex.exec(document.cookie);
    if (match) {
     var states = match[1].split("");
     for (var i = 0; i < states.length; i++)
      this.submenus[i].className = (states[i] == 0 ? "collapsed" : "");
    }
   }
};
SDMenu.prototype.toggleMenu = function(submenu) {
   if (submenu.className == "collapsed")
    this.expandMenu(submenu);
   else
    this.collapseMenu(submenu);
};
SDMenu.prototype.expandMenu = function(submenu) {
   var fullHeight = submenu.getElementsByTagName("span")[0].offsetHeight;
   var links = submenu.getElementsByTagName("a");
   for (var i = 0; i < links.length; i++)
    fullHeight += links[i].offsetHeight;
   var moveBy = Math.round(this.speed * links.length);
     
   var mainInstance = this;
   var intId = setInterval(function() {
    var curHeight = submenu.offsetHeight;
    var newHeight = curHeight + moveBy;
    if (newHeight < fullHeight)
     submenu.style.height = newHeight + "px";
    else {
     clearInterval(intId);
     submenu.style.height = "";
     submenu.className = "";
     mainInstance.memorize();
    }
   }, 30);
   this.collapseOthers(submenu);
};
SDMenu.prototype.collapseMenu = function(submenu) {
   var minHeight = submenu.getElementsByTagName("span")[0].offsetHeight;
   var moveBy = Math.round(this.speed * submenu.getElementsByTagName("a").length);
   var mainInstance = this;
   var intId = setInterval(function() {
    var curHeight = submenu.offsetHeight;
    var newHeight = curHeight - moveBy;
    if (newHeight > minHeight)
     submenu.style.height = newHeight + "px";
    else {
     clearInterval(intId);
     submenu.style.height = "";
     submenu.className = "collapsed";
     mainInstance.memorize();
    }
   }, 30);
};
SDMenu.prototype.collapseOthers = function(submenu) {
   if (this.oneSmOnly) {
    for (var i = 0; i < this.submenus.length; i++)
     if (this.submenus[i] != submenu && this.submenus[i].className != "collapsed")
      this.collapseMenu(this.submenus[i]);
   }
};
SDMenu.prototype.expandAll = function() {
   var oldOneSmOnly = this.oneSmOnly;
   this.oneSmOnly = false;
   for (var i = 0; i < this.submenus.length; i++)
    if (this.submenus[i].className == "collapsed")
     this.expandMenu(this.submenus[i]);
   this.oneSmOnly = oldOneSmOnly;
};
SDMenu.prototype.collapseAll = function() {
   for (var i = 0; i < this.submenus.length; i++)
    if (this.submenus[i].className != "collapsed")
     this.collapseMenu(this.submenus[i]);
};
SDMenu.prototype.memorize = function() {
   if (this.remember) {
    var states = new Array();
    for (var i = 0; i < this.submenus.length; i++)
     states.push(this.submenus[i].className == "collapsed" ? 0 : 1);
    var d = new Date();
    d.setTime(d.getTime() + (30 * 24 * 60 * 60 * 1000));
    document.cookie = "sdmenu_" + encodeURIComponent(this.menu.id) + "=" + states.join("") + "; expires=" + d.toGMTString() + "; path=/";
   }
};