Registers this class as a valid datatype for saving and loading via
        the datatype system.

def registerToDataTypes( cls ):
        """
        Registers this class as a valid datatype for saving and loading via
        the datatype system.
        """
        from projexui.xdatatype import registerDataType
        registerDataType(cls.__name__,
            lambda pyvalue:  pyvalue.toString(),
            lambda qvariant: cls.fromString(unwrapVariant(qvariant)))