How does the demo window scrolling of jQuery's website work?
<p><a href="http://api.jquery.com/scroll/" rel="nofollow">http://api.jquery.com/scroll/</a></p>

<p>When you scroll all the way down of the page, there is a demo window. And when we scroll to the top of that demo window, and we keep scrolling even our mouse is in the demo window, the whole page scrolls. And the whole page scrolls down when we do the same thing but scrolling to the bottom of the demo window.</p>

<p>Can anyone explain how does this work? It would be nice if I can see an actual code. Thank you!</p>