Method undo

src/backend/matrix/matrixcommands.h:296–298

		m_private_obj->setRowCells(m_row, m_first_column, m_last_column, m_values);
	}
	void undo() override {
		m_private_obj->setRowCells(m_row, m_first_column, m_last_column, m_old_values);
	}

private:
	MatrixPrivate* m_private_obj;