function AbrirVentanaTarget(url, ancho, alto, target)
{
	if (ancho == null)
		ancho = 400;

	if (alto == null)
		alto = 300;

	if(ancho>=screen.width)
    ancho=screen.width*0.9;

	if(alto>=screen.height)
    alto=screen.height*0.9;
		window.open(url, target, 'toolbar=no, location=no, directories=no, status=no, scrollbars=auto, resizable=no, copyhistory=no, width=' + ancho + ', height=' + alto + ', top=0');
}