var win = null;
function popup(url, width, height){
	wleft = (screen.width) ? (screen.width - width) / 2 : 0;
	wtop  = (screen.height) ? (screen.height - height) / 2 : 0;
	settings = 'height='+height+',width='+width+',top='+wtop+',left='+wleft+',scrollbars=no,titlebar=no,location=false,resizable=false';
	win = window.open(url, 'popupwin', settings);
}