SCROLL = function(obj, attr) {
	var interval;
	var offset = {
	'top': obj.offsetTop || 0,
	'height': obj.offsetHeight || 0
};
this.start = function(amount) {
/* Default setzen */
	attr.top = attr.top || 0;
	attr.width = attr.width || "auto";
/* Intervall starten */
interval = setInterval(
	function() {
	move(amount);
	},
	attr.time
	);
};

this.stop = function() {
	if (interval) {
	clearInterval(interval);
	}
}

function move(amount) {
/* Werte refreshen */
	attr.top += amount;
	attr.height += amount;
	offset.top -= amount;

/* Grenze überschritten? */
if (attr.top < 0 || attr.height > offset.height) {
	attr.top -= amount;
	attr.height -= amount;
	offset.top += amount;
	return;
}

/* Object bewegen */
	obj.style.clip = "rect(" + attr.top + "px " + attr.width + "px " + attr.height + "px 0)";
	obj.style.top = offset.top + "px";
	}
}

var scroll = new SCROLL(
	document.getElementById('content'),
	{
	'time':   60,
	'width':  240,
	'height': 250
	}
);