function popup(url,width,height,pageName) {
	if (pageName == undefined) {
		pageName = "_blank";
	}
	var winl = (screen.width - width) / 2;
	var wint = (screen.height - height) / 2;
	window.open(url,pageName,'width='+width+',height='+height+',toolbar=no,scrollbars=no,menubar=no,resizable=no,top='+wint+',left='+winl+'');
}