function menu (obj){
  var li = $(obj).getParent();
  var ul = li.getElement('ul');  
  ul.toggleClass('hide');  
  if ( li.hasClass('active' ) )
    li.removeClass('active')
  else if ( !ul.hasClass('hide') ) 
    li.addClass('active');
  }


window.addEvent('domready',function(){

var normal = 'images/mt/';
var hover = 'images/mt_hover/';

if ( $('mt') ){
  $('mt').getElements('a').each( function(el){ 
    var imgs = el.getElements('img');

    el.addEvent('mouseenter',function(){
        if ( imgs ){
        imgs.each ( function(img){
          img.set('src',img.get('src').replace(normal,hover));
          });
        }
      });

    el.addEvent('mouseleave',function(){
        if ( imgs ){
        imgs.each ( function(img){
          img.set('src',img.get('src').replace(hover,normal));
          });
        }
      });
    
    if ( imgs ){
      imgs.each ( function(img){
        new Element ('img',{'src':img.get('src').replace(normal,hover)});
        });
      }
    });
  }
});