Javascript这一段代码是什么意思，求大神指点！

x=o.offsetLeft;
y=o.offsetTop;
while(o=o.offsetParent)
{
x+=o.offsetLeft;
y+=o.offsetTop;
}
document.all.Calendar.style.left=x+2;
document.all.Calendar.style.top=y+20;
document.all.Calendar.style.visibility="visible";