void -rc search_spreadsheet (hwnd parent_window, wsproc -fp fp)
{
  w_in (parent_window, (hwnd window) [fp] {
                                            if (window->is_node ()) 
                                              search_spreadsheet (window, fp);
                                            else 
                                              if (fp (window)) {}
                                              else break;
                                          });
}