function init_nav() {
   var i = 0;
   var id = 0;
   for(i = 0; i < document.getElementsByTagName('ul').length; 
       i++) {
      if(document.getElementsByTagName('ul')[i].className == "opened" ) {
         
         id = document.getElementsByTagName('ul')[i].parentNode.id;
        //alert (i + ": " + id + ": " + document.getElementsByTagName('ul')[i].className);
        toggle(id, false);
      }
   }
   if(window.name.length > 0) {      
      load_nav();
   }
}

function toggle(id, save) {
   var ul = "ul_" + id;
   var img = "img_" + id;
   var ul_element = document.getElementById(ul);
   var img_element = document.getElementById(img);
   if(ul_element) {
       if(ul_element.className == 'closed' ) {
          ul_element.className = "opened";
          img_element.src = "/dna_images/template_d.n.a_hilfe/images/explorer/opened.gif";
       }
       
       else {
          ul_element.className = "closed";
          img_element.src = "/dna_images/template_d.n.a_hilfe/images/explorer/closed.gif";
       }
   }
   if(save == true) save_nav();
}

function save_nav() {
   var save = "";
   for(var i = 0; i < document.getElementsByTagName('ul').length;
   i++) {
      if((document.getElementsByTagName('ul')[i].className == 
      "opened" || 
      document.getElementsByTagName('ul')[i].className == 
      "closed") && document.getElementsByTagName('ul')[i].id != 
      'root') 
         save = save + document.getElementsByTagName('ul')[i].id 
         + "=" + document.getElementsByTagName('ul')[i].className 
         + ",";
   }
   if(save.lastIndexOf(",") > 0) 
      save = save.substring(0, save.lastIndexOf(","));
   window.name = save;
}

function load_nav() {
   
   var items = window.name.split(",");
   if(items.length > 0) {
      for(var i = 0; i < items.length; i++) {        
         var id_value = items[i].split("=");         
         if(id_value.length == 2 && document.getElementById(id_value[0]) ) {
            var id = id_value[0];  
            var value = id_value[1];
            if (document.getElementById(id).className == "closed"){
               document.getElementById(id).className = value;
               var img = "img_" + id.substring(3, id.length);
               var img_element = document.getElementById(img);
               if(value == "closed")
                  img_element.src = "/dna_images/template_d.n.a_hilfe/images/explorer/closed.gif";  
               else
                  img_element.src = "/dna_images/template_d.n.a_hilfe/images/explorer/opened.gif";
            }
         }
      }
   }
}