function scroll(div_id, direction, step, rotate, hide_scroll_up, hide_scroll_down)
{
	var div		= document.getElementById(div_id);
	
	switch (direction)
	{
		case 'up':
			if (rotate && ((div.scrollTop >= (div.scrollHeight - step))))
			{
				div.scrollTop = 0;
			} else {
				div.scrollTop += step;

				if ((0 != div.scrollTop%step) || div.scrollHeight == div.scrollTop)
				{
					document.getElementById(hide_scroll_down).style.visibility = 'hidden';
				} else {
					document.getElementById(hide_scroll_up).style.visibility = 'visible';
				}
			}
			break;
		case 'down':
			if (rotate && (div.scrollTop < step))
			{
				div.scrollTop = div.scrollHeight - step;
			} else {
				div.scrollTop -= step;

				if (0 == div.scrollTop)
				{
					document.getElementById(hide_scroll_up).style.visibility = 'hidden';
				} else {
					document.getElementById(hide_scroll_down).style.visibility = 'visible';
				}
			}
			break;
	}
		
}