If you have a div that sits at the bottom of a slideshow that you want to disappear when the user scrolls down, and then reappears when scrolls back to the top, you can follow the below example.

<div>
  <div class="a">
    A
  </div>
</div>​


$(window).scroll(function() {
  if ($(this).scrollTop() > 0) {
    $('.a').fadeOut();
  } else {
    $('.a').fadeIn();
  }
});

Hope it is useful for someone 🙂