function Abrir_Pop( wpop, ancho, alto )
{
	/*ancho=450; alto=250;*/
	if( ! ancho ) ancho = 700;	if( ! alto ) alto = 370;
	mileft = (screen.width - ancho) / 2;
	mitop = (screen.height - alto) / 2;

	myRef = window.open( wpop, '_blank', 'left='+mileft+',top='+mitop+',width='+ancho+',height='+alto+',toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=1,resizable=1' );
}