http://git.xfce.org/xfce/garcon/tree/garcon/garcon-menu-node.c#n239

Why the varlist of parameters? 
It makes problems with pygobject. I would have to override that function with a ridiculous small piece of code to get it working.

Error message of codegen:
Could not write function garcon_menu_node_create: varargs functions not supported


GarconMenuNode *
garcon_menu_node_create (GarconMenuNodeType node_type,
                         gpointer           first_value,
                         ...)
{
  GarconMenuNode *node;

  node = garcon_menu_node_new (node_type);

  switch (node_type)
    {
    case GARCON_MENU_NODE_TYPE_NAME:
    case GARCON_MENU_NODE_TYPE_DIRECTORY:
    case GARCON_MENU_NODE_TYPE_DIRECTORY_DIR:
    case GARCON_MENU_NODE_TYPE_APP_DIR:
    case GARCON_MENU_NODE_TYPE_FILENAME:
    case GARCON_MENU_NODE_TYPE_CATEGORY:
    case GARCON_MENU_NODE_TYPE_OLD:
    case GARCON_MENU_NODE_TYPE_NEW:
    case GARCON_MENU_NODE_TYPE_MENUNAME:
    case GARCON_MENU_NODE_TYPE_MERGE_DIR:
      node->data.string = g_strdup (first_value);
      break;

    case GARCON_MENU_NODE_TYPE_MERGE:
      node->data.layout_merge_type = GPOINTER_TO_UINT (first_value);
      break;

    case GARCON_MENU_NODE_TYPE_MERGE_FILE:
      node->data.merge_file.type = GPOINTER_TO_UINT (first_value);
      node->data.merge_file.filename = NULL;
      break;

    default:
      break;
    }

  return node;
}