function Centra(url, nombre, alto, ancho, conscroll) {
	var str = "height=" + alto + ",innerHeight=" + alto;
	str += ",width=" + ancho + ",innerWidth=" + ancho;
	if (window.screen) {
		var ah = screen.availHeight - 30;
		var aw = screen.availWidth - 10;
		var xc = (aw - ancho) / 2;
		var yc = (ah - alto) / 2;
		str += ",left=" + xc + ",screenX=" + xc;
		str += ",top=" + yc + ",screenY=" + yc;
	}
	str += ",toolbar=no,location=no,directories=no,status=no,menubar=no,resizable=no,copyhistory=no,scrollbars="
	if (conscroll = 1) {
		str += "yes"
	}else{
		str += "no"
	}
	window.open(url, nombre, str);
}