Dispatch handling of this event to a receiver.

        This method will invoke ``receiver._column_data_changed`` if it exists.

def dispatch(self, receiver):
        ''' Dispatch handling of this event to a receiver.

        This method will invoke ``receiver._column_data_changed`` if it exists.

        '''
        super(ColumnDataChangedEvent, self).dispatch(receiver)
        if hasattr(receiver, '_column_data_changed'):
            receiver._column_data_changed(self)