title: How to addclass with timeout
body: <p>Don't know why it's not working, i think the code is fine - could you tell me what is wrong? I need to add some class after some time interval... </p>
  
  <pre><code>$('.main_menu ul li').mouseenter(function(){
      setTimeout(function(){
          $(this).children('.sub_menu_main').addClass('opened')
      },200);
  });
  $('.main_menu ul li').mouseleave(function(){
      $(this).children('.sub_menu_main').removeClass('opened')
  });
  </code></pre>