function preloadImage(imageurl) {
  image = new Image();
  image.src = imageurl;
}

function fade(imageId) {
  internFade(imageId, 0, 1);
}

function internFade(imageId, from, to, oncomplete) {
  image = document.getElementById(imageId);
  if (image == null)
    return;
  setOpacity(image, from);
  image.style.visibility = 'visible';

  animation = new Animation({
    object: image,
    from: from,
    to: to,
    tweenType: 'quicklinear',
    ontween: setOpacity,
    oncomplete: function() {
      setOpacity(image, to); 
      if (oncomplete)
        oncomplete();   
    }
  });    
  animation.start();
}

function setOpacity(obj, opacity) {
  // Soll sehr alten Bug bezüglich Flackern im Firefox beheben.
  // Schneidet bei Firefox aber nun bei jedem Zeilenende eine Pixellinie vom Text ab.
  //opacity = (opacity == 1) ? 0.99999 : opacity;
  
  // IE/Win
  obj.style.filter = "alpha(opacity:"+(opacity*100)+")";
  
  // Safari<1.2, Konqueror
  obj.style.KHTMLOpacity = opacity;
  
  // Older Mozilla and Firefox
  obj.style.MozOpacity = opacity;
  
  // Safari 1.2, newer Firefox and Mozilla, CSS3
  obj.style.opacity = opacity;
  
  
  //setAngle(obj, opacity * 0.1 + 0.9);
}