function popup( url,largWin,altWin) {
	var largSchermo = screen.availWidth;
	var altSchermo = screen.availHeight;
	var left = ( largSchermo - largWin ) / 2;
	var top = ( altSchermo - altWin ) / 2;
	window.open( url, "main", "width=" + largWin + ", height=" + altWin + ", top=" + top +", left=" + left + ", scrollbars=no, location=no, resizable=no");
}