//
// scrollchaser.js
//
// Require mootools.js
// http://mootools.net/
//
// 2008.1.28
//
var el;
var curScrlTop;
var initTop;
var interval;
//
//window.addEvent('domready', function()
//{
//	Setting();
//});
(function()
{
	if(window.addEventListener) window.addEventListener('load',Setting,false);
	else if(window.attachEvent) window.attachEvent('onload',Setting);
})();
//
function Setting()
{
	try {
		window.addEventListener('scroll', ScrollEvent, false);
    } catch (e) {
		if(IsIE && document.compatMode!="BackCompat")
		{
			window.attachEvent('onscroll',ScrollEvent);
		}
    }
	try {
		if(IsIE) document.attachEvent('onmousewheel', WheelEvent);
	} catch (e) {
		//
	}
	//
	el=$('back_number_list');
	el.setStyle( 'position', 'absolute' );
	initTop=el.getTop();
	interval=200;
}
function ScrollEvent()
{
	curScrlTop = (document.body.scrollTop||document.documentElement.scrollTop)+20;
	var myInt = setInterval(function()
		{
			var myTop=el.getTop();
			var d=curScrlTop-myTop;
			if(Math.abs(d)>1) {
				if( curScrlTop>=initTop )
				{
					var y = myTop+d/3;
					el.setStyle('top',y);
					//el.appendText(d+'\n');
				} else {
					el.setStyle('top',initTop);
					clearInterval(myInt);
				}
			} else {
				el.setStyle('top',curScrlTop);
				clearInterval(myInt);
				//el.appendText('interval cleared.');
			}
		},interval);
}
function WheelEvent(event)
{
	var scrlBtm = document.body.offsetHeight-document.documentElement.clientHeight;
	if( curScrlTop>initTop && curScrlTop<scrlBtm )
	{
		var delta = event.wheelDelta;
		var myTop=el.getTop();
		el.setStyle('top',myTop+delta);
		//el.appendText(scrlBtm+'/'+curScrlTop+'\n');
	}
}
function IsIE(){
    if(navigator){
        if(navigator.userAgent){
            if(navigator.userAgent.indexOf("MSIE") != -1){
                return true;
            }
        }
    }
    return false;
}