function zoom(pagina, w, h){
	var left=(screen.width - w)/2;
	var top=(screen.height- h)/2
	miaFin=window.open(pagina, "zoom", "width=" + w + ",height=" + h + ", left="+left+", top="+top+", directories=no, location=no, menubar=no, resizable=no, status=no, toolbar=no, scrollbars=no");
	miaFin.focus();
}