message: macOS: Add placeholder menus into the global menu
  Still not the ideal of having a native single menu, but at least have
  placeholder items so that the menu appears complete at first sight.
diff: <accel>Ctrl+A</accel>
  </object>
  </object>
  + <object class="wxMenu" name="menu_view">
  + <label>_View</label>
  + </object>
  + <object class="wxMenu" name="menu_catalog">
  + <label>C_atalog</label>
  + </object>
  + <object class="wxMenu" name="menu_go">
  + <label>_Go</label>
  + </object>
  <object class="wxMenu" name="menu_window" platform="mac">
  <label>Window</label>
  </object>
  