code: func SeparatorMenuItemNew() (*SeparatorMenuItem, error) {
  	c := C.gtk_separator_menu_item_new()
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	return wrapSeparatorMenuItem(glib.Take(unsafe.Pointer(c))), nil
  }
docs: // SeparatorMenuItemNew is a wrapper around gtk_separator_menu_item_new().