function preloadIcons()
{
  var imageObj = new Image();
  imageObj.src = 'images/label_icon_rollover.gif';
  imageObj.src = 'images/patch_icon_rollover.gif';
  imageObj.src = 'images/transfer_icon_rollover.gif';
  imageObj.src = 'images/pen_icon_rollover.gif';
  imageObj.src = 'images/cling_icon_rollover.gif';
  
  imageObj = null;
}

function rollover(imageId, imageName)
{
  document.getElementById(imageId).src = imageName;
  return;
}

preloadIcons();