title: issue when unchecking radio buttons with jQuery
body: <p>Here is a group of radio buttons: </p>
  
  <pre><code>&lt;input id="Radio1" type="radio" name="g" /&gt;rbtn 1
  &lt;input id="Radio2" type="radio" name="g" /&gt;rbtn 2
  &lt;input id="Radio3" type="radio" name="g" /&gt;rbtn 3
  &lt;div id="test"&gt;Click this div to uncheck selected radio button&lt;/div&gt;
  </code></pre>
  
  <p>And my jQuery code looks like this:</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
      $(document).ready(function () {
          $("#test").click(function () {
              //alert("clicked");
              $(":checked").removeAttr("checked");
              //$(":checked").attr("checked", false);
          });
      });
  &lt;/script&gt;
  </code></pre>
  
  <p>For some reason, I can't see any radio button has been unchecked when I click the div. I have also tried to use attr() method to set checked equals false, but still no luck. Could anyone give me a little hint here?</p>
  
  <p>EDIT:</p>
  
  <p>I don't know if it's because using ASP page causes the problem. I doubt so though. Just can't think of anything else that stops it working. So weird. </p>
  
  <p>EDIT2:</p>
  
  <p>I think I have found the actual cause. The problem seems to be the <code>DOCTYPE</code>. I wouldn't have thought of that in the first place, really. T_T</p>
  
  <p><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;</code></p>
  
  <p>The above was I originally had with my HTML, and when I took it out, jQuery seemed to be working all right :)</p>
  
  <p>Any explanation on that? </p>
  
  <p>EDIT3:</p>
  
  <p>I think by removing <code>DOCTYPE</code> we will be using IE's quirks mode. So for non-IE browsers, it actually won't help. </p>
  
  <p>FINAL EDIT:</p>
  
  <p><strong>Finally I can stop scratching my head by upgrading jQuery code to the latest version. Indeed, jQuery 1.6.2 is a lot better than jQuery 1.6. :D</strong></p>