function scroller_scroll() {
	var el = document.getElementById('scroller');
	if(!el) return;

	var size = common_getSize(el);
//	showProps(size);
	var docHeight = el.scrollHeight / 2;
//	alert(docHeight);
	var pos = el.scrollTop;
//	alert(pos);

	var wrap = docHeight;

//	alert('el.height='+size.height+' docHeight='+docHeight+' el.scrollTop='+el.scrollTop);

	if(pos < wrap) {
		pos += 1;
		el.scrollTop = pos;
	} else {
		pos += 1;
		pos -= docHeight;
		el.scrollTop = pos;
	}

	window.setTimeout(scroller_scroll, 30);
}