Font size in QGraphicsTextItem

I add QGraphicsTextItem to graphics scene and then change its font family and font size. It works ok, but when I click and/or move my item font size changes to the 12 size. Actually its changed in QGraphicsTextItem::mouseReleaseEvent().
What is needed to force QGraphicsTextItem keep font size? Thanks in advance.

I found where fonts size changes but still cant understand why

Code:

---

void MyPlainTextItem::mouseReleaseEvent ( QGraphicsSceneMouseEvent * mouseEvent )
{
	MyTW::self()->fillTable(props); //Filling property table for this item when clicked. If I delete this line all works fine.
	cout << this << " is selected!" << endl;
	QGraphicsTextItem::mouseReleaseEvent(mouseEvent);
}

---

This is fillTable function, it has nothing to do with QGrpahicsTextItem but still somehow it changes font size.

Code:

---

void MyTW::fillTable(QMap<QString,QString> map)
{
	clear();
	setRowCount(map.size());
	QTableWidgetItem* twi = new QTableWidgetItem();
	twi->setText(QString::fromLocal8Bit("оБЪЧБОЙЕ"));
	setHorizontalHeaderItem(0,twi);
	QTableWidgetItem* twi_1 = new QTableWidgetItem();
	twi_1->setText(QString::fromLocal8Bit("ъОБЮЕОЙЕ"));
	setHorizontalHeaderItem(1,twi_1);
	QMapIterator<QString,QString> i(map);
	int j =0;
	while (i.hasNext())
	{
		i.next();
		QTableWidgetItem* item = new QTableWidgetItem();
		item->setText(i.key());
		setItem(j,0,item);
		QTableWidgetItem* item_1 = new QTableWidgetItem();
		item_1->setText(i.value());
		setItem(j,1,item_1);
		j++;
	}
}

---