function popup(url, sx, sy)
{
	var winl = (screen.width-sx)/2;
	var wint = (screen.height-sy)/2;
	var finestra = 'finestra';
	popupwin=window.open(url,finestra,"scrollbars=no, resizable=yes, toolbar=no, location=no, directories=no, status=no, menubar=no, top="+wint+",left="+winl+",width="+sx+",height="+sy+"");
}