<A target="_blank" href="http://dontpanic82.blogspot.com/2010/01/xpages-developer-tool-deep-dive-into.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+dontpanic82+%28DontPanic+-+a+blog+about+Lotus+Notes+%2F+Domino%29">Tommy Valand has posted a demo app with a custom control you can download</A> and study to see how the API works. He's also posted an animated GIF showing it in action.