title: addClass and removeClass not working in Internet Explorer
body: <p>jQuery functions addClass and removeClass do not work properly when I use them to change the appearance of a checkbox in Internet Exploer (IE). However, they work fine in other browsers. </p>
  
  <p>Here is sample code to illustrate my problem:</p>
  
  <pre><code>$('input:#chkbox').click(function()
      {
          //if($(this).is(":checked")){
          if($('input:#chkbox').is(":checked"))
          {
              $('input:#chkbox').next("label").addClass("etykieta_wybrana");
          }
          else
          {
              $('input:#chkbox').next("label").removeClass("etykieta_wybrana");
          }
      });
  </code></pre>
  
  <p>To further test this, you can run the code using jsFiddler (does not work in IE):
  <a href="http://jsfiddle.net/tejek/pZJMd/" rel="noreferrer">http://jsfiddle.net/tejek/pZJMd/</a></p>