public function add_shortcut(string $id): ?string
  {
    if (
      ($bit = $this->pref->get_bit($id, false)) &&
      ($id_option = $this->from_path('shortcuts')) &&
      ($c = $this->pref->get_class_cfg())
    ){
      if ( $id_menu = $this->pref->get_by_option($id_option) ){
        $id_menu = $id_menu[$c['arch']['user_options']['id']];
      }
      else {
        $id_menu = $this->pref->add($id_option, [$c['arch']['user_options']['text'] => _('Shortcuts')]);
      }
      if (
        !empty($id_menu) &&
        ($arch = $c['arch']['user_options_bits'])
      ){
        if (
          ($bits = $this->pref->get_bits($id_menu, false, false)) &&
          ( \bbn\x::find($bits, [$arch['id_option'] => $bit[$arch['id_option']]]) !== false)
        ){
          return null;
        }
        return $this->pref->add_bit($id_menu, [
          $arch['id_option'] => $bit[$arch['id_option']],
          $arch['text'] => $bit[$arch['text']],
          $arch['cfg'] => $bit[$arch['cfg']],
          $arch['num'] => $this->pref->next_bit_num($id_menu) ?: 1
        ]);
      }
    }
    return null;
  }