function setupCascadingNav()
{
  list_items = document.getElementById('nav').getElementsByTagName('li');
  for(i=0;i<list_items.length;i++){
    list_item = list_items[i];
    list_item.onmouseover = function(){
      this.className = 'over';
      if(child_list = findChildList(this)){
        child_list.style.display = 'block';
      }
    }
    list_item.onmouseout = function(){
      this.className = '';
      if(child_list = findChildList(this)){
        child_list.style.display = 'none';
      }
    }
  }
}

function findChildList(list_item)
{
  child_list = false;
  for(n=0;n<list_item.childNodes.length;n++){
    child_node = list_item.childNodes[n];
    if(child_node.nodeName == 'UL'){
      child_list = child_node;
      break;
    }
  }
  return child_list;
}


addLoadEvent(setupCascadingNav);