window.onload = function () {
  
  var container = $('div.sliderGallery');
  var ul = $('ul', container);

  var itemsWidth = ul.innerWidth() - container.outerWidth();

  $('.slider', container).slider({
    min: 0,
    max: itemsWidth,
    handle: '.handle',
    stop: function (event, ui) {
      ul.animate({'left' : ui.value * -1}, 800);
    },
    slide: function (event, ui) {
      ul.css('left', ui.value * -1);
    }
  });
};