function stampa_ticket(http, pk_ticket)
  {
    w = 750;
    h = 500;
    x = (screen.width - w) / 2;
    y = (screen.height - h) / 2;
              
    window.open(http + '/stampa/ticket.php?ticket=' + pk_ticket,'','width='+w+',height='+h+',top='+y+',left='+x+',scrollbars=yes');        
  }