function initScroll(w, h)
{
	var theRoot, theThumb, theScroll;
	var thumbTravel, ratio;

	if(!w) w = 418;
	if(!h) h = 300;
	thumbHeight = 40;
	
	theScroll = new ypSimpleScroll("scroll", 0, 0, w, h);
		
	addLoadListener(function() {
		theRoot   = document.getElementById("scrollBox");
		theThumb  = document.getElementById("thumb");

		theScroll.load();

		Drag.init(theThumb, null, w, w, 0, h-thumbHeight);

		// the number of pixels the thumb can travel vertically (max - min)
		thumbTravel = theThumb.maxY - theThumb.minY;

		// the ratio between scroller movement and thumbMovement
		ratio = theScroll.scrollH / thumbTravel;

		theThumb.onDrag = function(x, y) {
			theScroll.jumpTo(null, Math.round((y - theThumb.minY) * ratio));
		}
	});
}