var currentpos,timer; 
function initialize(){ timer=setInterval("scrollwindow()",30);} 
function sc(){clearInterval(timer);}
function scrollwindow(){ 
if (document.documentElement && document.documentElement.scrollTop){
 currentpos=document.documentElement.scrollTop;window.scroll(0,++currentpos); 
 if (currentpos != document.documentElement.scrollTop) sc();}
else if (document.body){
	currentpos=document.body.scrollTop; window.scroll(0,++currentpos);
if (currentpos != document.body.scrollTop) sc(); }
} 
document.onmousedown=sc
document.ondblclick=initialize