var last_left_url = "";
  var last_right_url = "";
  function check_urls()
  {
    if (frames[0].location.pathname != last_left_url || frames[1].location.pathname != last_right_url)
    {
      location.hash = frames[0].location.pathname+
        "__"+frames[1].location.pathname ;
      last_left_url = frames[1].location.pathname ;
      last_right_url = frames[0].location.pathname ;
    }
  }

  function note_url()
  { 
    if ( window.top.frames[0] == window.self )
    {
      last_left_url = location.pathname ;
    }
    else
    { 
      last_right_url = location.pathname ;  
    }
  }


  function set_urls()
  {
    window.top.location.hash = window.frames['side'].location.pathname+"__"+window.frames['main'].location.pathname ;
  }

  function load_urls()
  {
    var urls = document.location.hash;
    var double_underscore_position = urls.search("__") ;
    if (double_underscore_position < 2 || urls.length - double_underscore_position < 3)
    { 
      return ;
    }
    var left_url = urls.substring(1, double_underscore_position) ;
    var right_url = urls.substring(double_underscore_position + 2) ;
    var hostname = window.top.location.hostname ;
    window.top.frames[0].location = "http://"+hostname+left_url ;
    window.top.frames[1].location = "http://"+hostname+right_url ;

  }  

  function scroll()
  {
    location.assign(location) ;
  }