Undocumented --timeout option in zenity

I noticed that there was an option in zenity that was not documented: --timeout, which specifies a time for the dialog to close. I noticed this looking at zenity's code:

  {
    "timeout",
    '\0',
    0,
    G_OPTION_ARG_INT,
    &zenity_general_timeout_delay,
    N_("Set dialog timeout in seconds"),
    /* Timeout for closing the dialog */
    N_("TIMEOUT")
  },

I've filled a bug report to Debian, and mailed the maintainer, Lucas Rocha, about it.