JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
  <head>
    <title>Popup :: Failing Dropdown Experiment</title>
    <link rel="stylesheet" href="http://code.jquery.com/ui/1.9.1/themes/base/jquery-ui.css">
  </head>
  <body>
    <form id="form1">
      <select>
      </select>
    </form>

    <div id="my-dialog">
      <form id="form2">
        <select>
          <option>option-2a</option>
          <option>option-2b</option>
        </select>
      </form>
    </div>
    
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
    <script src="http://code.jquery.com/ui/1.9.1/jquery-ui.js"></script>
    <script type="text/javascript">
      $(function() {
        $("#my-dialog").dialog({
          modal: true,
          open: function(){
            $('body').css('overflow','hidden'); // suspect
            $('#form2 select').focus();
          }
        });
      });
    </script>
  </body>
</html>