fadein / fadeout div on checkbox select / unselect
<p>I am trying to bring up a menu when any of the checkbox is selected, as you can see in screenshot below, it shows the number of selections and the menu also disappears when none is select.</p>

<p><img src="http://i38.tinypic.com/200tow0.jpg" alt="alt text" /></p>

<p>I am able to bring up the menu with this code</p>

<pre><code>$("input[name='id[]']").focus(function(){
    $("#menu").fadeIn();
});
</code></pre>

<p>However, i dont know how to hide it when the checkboxes are unselected and how to count number of selections.</p>

<p>Thank You.</p>
