Q:

on scroll of child div scroll parent div

i want a #nav to be on top but above the #nav there is some text.on scroll of the #child div i should be able to scroll main scroll bar of the body then the #nav should be fixed on top!and there should be scrolling for only #child div.
heres the reference..
http://jsfiddle.net/maUYK/
  <p>text</p>
  <p>text</p>
  <p>text</p>
  <p>text</p>
        <ul id="nav">
        <li><a href="#">About Us</a></li>
        <li><a href="#">Our Products</a></li>
        <li><a href="#">FAQs</a></li>
        <li><a href="#">Contact</a></li>
        <li><a href="#">Login</a></li>
        </ul>
  <div id="child">
  <table>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
         <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
        <tr><td>a</td><td>b</td><td>c</td></tr>
  </table>
  </div>

A:

#nav{
    position:absolute;
       top:200px;
     left:0;
     }

     #nav.fixed{
     position:fixed;
         top:10px;
        }

Use the above styles to position navigation and fix after the scroll
For info you can visit this link - http://addyosmani.com/blog/rocketbar/

