// gives up and down scroll buttons to images, spans, ... named up_name, down_name, respectively.
// will keep the default scroll_box's style overflow if it encounters errors (so make overflow: auto;)

// usage: put this after the scrollbox div:  var div_scroll1 = new TextScroll('div_scroll1', 'scroll_box');
function TextScroll(scrollname, div_name, up_name, down_name)
{
	this.div_name = div_name;
	this.name = scrollname;
	this.scrollCursor = 0;
	this.speed = 10;
	this.timeoutID = 0;
	this.div_obj = null;
	this.up_name = up_name;
	this.dn_name = down_name;

	{
		if (document.getElementById) {
			div_obj = document.getElementById(this.div_name);
			if (div_obj) {
				this.div_obj = div_obj;
				this.div_obj.style.overflow = 'hidden';
			}
			div_up_obj = document.getElementById(this.up_name);
			div_dn_obj = document.getElementById(this.dn_name);
			if (div_up_obj && div_dn_obj) {
				div_up_obj.setAttribute("onmouseover", scrollname + ".scrollUp();")
				div_up_obj.setAttribute("onmouseout", scrollname + ".stopScroll();")

				div_dn_obj.setAttribute("onmouseover", scrollname + ".scrollDown();")
				div_dn_obj.setAttribute("onmouseout", scrollname + ".stopScroll();")
			}
		}
	}

	this.stopScroll = function() {
		clearTimeout(this.timeoutID);
	}

	this.scrollUp = function() {
		if (this.div_obj) {
			this.scrollCursor = (this.scrollCursor - this.speed) < 0 ? 0 : this.scrollCursor - this.speed;
			this.div_obj.scrollTop = this.scrollCursor;
			this.timeoutID = setTimeout(this.name + ".scrollUp()", 60);
		}
	}

	this.scrollDown = function() {
		if (this.div_obj) {
			this.scrollCursor += this.speed;
			this.div_obj.scrollTop = this.scrollCursor;
			this.timeoutID = setTimeout(this.name + ".scrollDown()", 60);
		}
	}

	this.resetScroll = function() {
		if (this.div_obj) {
			this.div_obj.scrollTop = 0;
			this.scrollCursor = 0;
		}
	}
}