Hi. how can i scroll vertical slider to position before table update?

i am tried to some options, but it sometime works ok and sometime is scrolled to different position.

Qt Code: 
  1. int sliderPosition = ui->tableWidget->row(ui->tableWidget->itemAt(0,0));
  2.  
  3. ui->tableWidget->clearContents();
  4. ui->tableWidget->setRowCount(0);
  5. ui->tableWidget->setSortingEnabled(false);
  6.  
  7. //add new rows
  8.  
  9. ui->tableWidget->setSortingEnabled(true);
  10.  
  11. ui->tableWidget->scrollToItem( ui->tableWidget->item( sliderPosition, 0));
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or

Qt Code: 
  1. int sliderPosition = ui->tableWidget->verticalScrollBar()->sliderPosition();
  2.  
  3. ui->tableWidget->clearContents();
  4. ui->tableWidget->setRowCount(0);
  5. ui->tableWidget->setSortingEnabled(false);
  6.  
  7. //add new rows
  8.  
  9. ui->tableWidget->setSortingEnabled(true);
  10.  
  11. ui->tableWidget->verticalScrollBar()->setSliderPosition(sliderPosition);
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but both with same result.