//function to show a popup window
function popup(url, scroll, width, height)
{
	var w = width;
	var h = height;
	var winl = (screen.width - w) / 2;
	var wint = (screen.height - h) / 2;
	window.open(url,"popupwin","scrollbars="+scroll+",width="+w+",height="+h+",top="+wint+",left="+winl+",resizable=yes,status=no,location=no,toolbar=no,menubar=no");
	return false;
}