/** This is high-level function; REPLACE IT WITH YOUR CODE.
 * It must react to delta being more/less than zero.
 */
function handle(delta) {
	var retVal;
	if (navigator.appName.indexOf("Microsoft") != -1) {
		retVal=window.external.getMouseDelta(delta);
	} else {
		retVal=document.external.getMouseDelta(delta);
	}
	return retVal;
}

function wheel(event){
	var delta = 0;
	if(!event)event=window.event;
	if(event.wheelDelta){
		delta=event.wheelDelta/120; 
		if(window.opera)delta=-delta;
	}else if(event.detail){
		delta=-event.detail/3;
	}
	if(delta)
		handle(delta);
        if(event.preventDefault)
        event.preventDefault();
        event.returnValue=false;
}

/* Initialization code. */
if (window.addEventListener)
	window.addEventListener('DOMMouseScroll',wheel,false);
	window.onmousewheel=document.onmousewheel=wheel;