Returns the list of child keys for this settings instance.
        
        :return     [<str>, ..]

def childKeys(self):
        """
        Returns the list of child keys for this settings instance.
        
        :return     [<str>, ..]
        """
        if self._customFormat:
            return self._customFormat.childKeys()
        else:
            return super(XSettings, self).childKeys()