Event.observe(window, "load", function() {
 var m_menus = $$("#menu li.m_menu");

 function mover_handler() {
  $(this).addClassName("hover");
 }

 function mout_handler() {
  $(this).removeClassName("hover");
 }
 m_menus.each(function(m_menu) {
  Event.observe(m_menu, "mouseover", mover_handler.bind(m_menu));
  Event.observe(m_menu, "mouseout", mout_handler.bind(m_menu));
 });
});