Set the value of the given index row to its default

        :param index:
        :type index:
        :returns:
        :rtype:
        :raises:

def restore_default(self, index):
        """Set the value of the given index row to its default

        :param index:
        :type index:
        :returns:
        :rtype:
        :raises:
        """
        spec = self.get_configspec_str(index)
        if spec is None or isinstance(spec, Section):
            return
        try:
            default = self._vld.get_default_value(spec)
            defaultstr = self._val_to_str(default)
            self.setData(index, defaultstr)
        except KeyError:
            raise ConfigError("Missing Default Value in spec: \"%s\"" % spec)