title: Malihu jQuery Custom Scrollbar with Select 2
body: <p>Scrollbar shows only on first opening and no more.
  What I did wrong?</p>
  
  <pre><code>$('.select').on('select2:open', function () {
      function showScroll() {
          $('.select2-results__options').mCustomScrollbar();
      }
      setTimeout(showScroll, 1);
  });
  </code></pre>