Reimplements the :meth:`*.paintEvent` method.

        :param event: QEvent.
        :type event: QEvent

def paintEvent(self, event):
        """
        Reimplements the :meth:`*.paintEvent` method.

        :param event: QEvent.
        :type event: QEvent
        """

        super(type(self), self).paintEvent(event)

        show_message = True
        model = self.model()
        if issubclass(type(model), GraphModel):
            if model.has_nodes():
                show_message = False
        elif issubclass(type(model), QAbstractItemModel) or \
                issubclass(type(model), QAbstractListModel) or \
                issubclass(type(model), QAbstractTableModel):
            if model.rowCount():
                show_message = False

        if show_message:
            self.__notifier.show_message(self.__message, 0)
        else:
            self.__notifier.hide_message()