NSSavePanel (and NSOpenPanel, as a subclass) supports a `message` (via `setMessage:message` in Obj-C), which allows a message to be displayed even when the panel is attached to a parent. Right now, `title` is useless for attached dialogs.

atom/browser/api/atom_api_dialog.cc
mate::Arguments* args) {
  v8::Local<v8::Value> peek = args->PeekNext();
  file_dialog::OpenDialogCallback callback;
  if (mate::Converter<file_dialog::OpenDialogCallback>::FromV8(args->isolate(),
                                                               peek,
                                                               &callback)) {
    file_dialog::ShowOpenDialog(settings, callback);
  } else {
    std::vector<base::FilePath> paths;
    if (file_dialog::ShowOpenDialog(settings, &paths))
      args->Return(paths);
  }
}
void ShowSaveDialog(const file_dialog::DialogSettings& settings,