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

  // adding events
  $('menuleft').addEvents({
    mouseenter: function(){
      // Always sets the duration of the tween to 1000 ms and a bouncing transition
      // And then tweens the height of the element
      this.set('tween', {
        duration: 1000,
        transition: Fx.Transitions.Bounce.easeOut // This could have been also 'bounce:out'
      }).tween('height', '120px');
    },
    mouseleave: function(){
      // Resets the tween and changes the element back to its original size
      this.set('tween', {}).tween('height', '20px');
    }
  });

});