var x = 50,y = 60 
var xin = true, yin = true 
var step = 1 
var delay = 50 
var obj=document.getElementById("RDivAd") 
function floatAD() { 
var L=T=0 
var R= document.body.clientWidth-obj.offsetWidth 
var B = document.body.clientHeight-obj.offsetHeight 
obj.style.left = x + document.body.scrollLeft 
obj.style.top = y + document.body.scrollTop 
x = x + step*(xin?1:-1) 
if (x < L) { xin = true; x = L} 
if (x > R){ xin = false; x = R} 
y = y + step*(yin?1:-1) 
if (y < T) { yin = true; y = T } 
if (y > B) { yin = false; y = B } 
} 
var itl= setInterval("floatAD()", delay) 
obj.onmouseover=function(){clearInterval(itl)} 
obj.onmouseout=function(){itl=setInterval("floatAD()", delay)}