function ventanaGenerica(popupURL, ancho, alto) 
{ 
    var popup = window.open(popupURL,"_blank",'toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=1,resizable=1, width='+ancho+', height='+alto+', left=5, top=5'); 
  if( navigator.appName.substring(0,8) == "Netscape" ) { 
    popup.location = popupURL; 
    popup.focus(); 
  } 
}