def warning(self, msg: str) -> None:
        """
        Write a warning message to the Windows Application log
        (± to the Python disk log).
        """
        # Log messages go to the Windows APPLICATION log.
        # noinspection PyUnresolvedReferences
        s = "{}: {}".format(self.fullname, msg)
        servicemanager.LogWarningMsg(s)
        if self.debugging:
            log.warning(s)