I found where fonts size changes but still cant understand why

Qt Code:
  1. void MyPlainTextItem::mouseReleaseEvent ( QGraphicsSceneMouseEvent * mouseEvent )
  2. {
  3. MyTW::self()->fillTable(props); //Filling property table for this item when clicked. If I delete this line all works fine.
  4. cout << this << " is selected!" << endl;
  5. QGraphicsTextItem::mouseReleaseEvent(mouseEvent);
  6. }
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This is fillTable function, it has nothing to do with QGrpahicsTextItem but still somehow it changes font size.

Qt Code:
  1. void MyTW::fillTable(QMap<QString,QString> map)
  2. {
  3. clear();
  4. setRowCount(map.size());
  5. twi->setText(QString::fromLocal8Bit("оБЪЧБОЙЕ"));
  6. setHorizontalHeaderItem(0,twi);
  7. twi_1->setText(QString::fromLocal8Bit("ъОБЮЕОЙЕ"));
  8. setHorizontalHeaderItem(1,twi_1);
  9. QMapIterator<QString,QString> i(map);
  10. int j =0;
  11. while (i.hasNext())
  12. {
  13. i.next();
  14. item->setText(i.key());
  15. setItem(j,0,item);
  16. item_1->setText(i.value());
  17. setItem(j,1,item_1);
  18. j++;
  19. }
  20. }
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