function set_page_footer()
{
	var a = document.getElementById("rightdiv");
	var b = document.getElementById("centerdiv");
	var c = document.getElementById("leftdiv");
	var maxheight = Math.max(a.offsetHeight,Math.max(b.offsetHeight,c.offsetHeight))
	a.style.height = maxheight + 'px';
	b.style.height = maxheight + 'px';
	c.style.height = maxheight+5 + 'px';
}