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";
     attr.height = attr.height || "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 + " " + attr.width + " " + attr.height + " 0)";
     obj.style.top = (offset.top) + "px";
   }
}