window.addEvent('domready', function(){ 
	  var totIncrement		= 0;
	  var increment			= 600;
	  var maxRightIncrement	= increment*(-7);
	  var fx = new Fx.Style('myList', 'margin-left', {
				duration: 2200,
				transition: Fx.Transitions.Back.easeInOut,
				wait: true
	   });

	  // events button "previous"----
	  $('previous').addEvents({ 
          'click' : function(event){ 
		  if(totIncrement<0){
					totIncrement = totIncrement+increment;
					fx.stop()
					fx.start(totIncrement);
				}
			}			  	  
      }); 

	  // events button "next" -------
  	  $('next').addEvents({ 
          'click' : function(event){ 
			 if(totIncrement>maxRightIncrement){
				 totIncrement = totIncrement-increment;
		    	fx.stop()
				fx.start(totIncrement);
			}
          }		  		  
      })


});