function doZoom(size,height){
  document.getElementById('zoom').style.fontSize=size+'px';
  document.getElementById('zoom').style.lineHeight=height+'pc';
 }
var currentpos,timer;

function initialize()
{
timer=setInterval("scrollwindow()",50);
}

function sc(){
clearInterval(timer);
}

function scrollwindow()
{
currentpos=document.body.scrollTop;
window.scroll(0,++currentpos);
if (currentpos != document.body.scrollTop)
sc();
}
document.onmousedown=sc
document.ondblclick=initialize