function handleScroll(){ 
document.getElementById("downmenu").style.top = (document.body.offsetHeight*0.87 + document.body.scrollTop) +"px"; 
} 
function pop(){  
var toogle = document.getElementById("downmenulist"); 
if(toogle.style.display == "" || toogle.style.display == "none"){ 
toogle.style.display = "block"; 
document.getElementById("menuimg").src = "/images/up.gif";
}else{ 
toogle.style.display = "none"; 
document.getElementById("menuimg").src = "/images/down.gif";
} 
}
function init(){
document.body.onscroll="handleScroll()";
document.body.onload="handleScroll()";
document.getElementById("downmenu").onmouseover=pop;
document.getElementById("downmenu").onmouseout=pop;
}
window.onload=init;