var div_scroll
function init(){
	div_scroll = new TextScroll('div_scroll', 'scroll_box', 'scroll_up', 'scroll_down');
}

// 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 = 20;
    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.onmouseover = function() { eval(scrollname + ".scrollUp();") };
				div_up_obj.onmouseout = function() { eval(scrollname + ".stopScroll();") };
				
				div_dn_obj.onmouseover = function() { eval(scrollname + ".scrollDown();") };
				div_dn_obj.onmouseout = function() { eval(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;
		if (this.div_obj.scrollTop == this.scrollCursor) {
			this.timeoutID = setTimeout(this.name + ".scrollDown()", 60);
		} else {
			this.scrollCursor = this.div_obj.scrollTop;
		}
	}
}

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