QTableView/QTableWidget and resizeRowsToContents resizes wrongly

[alterro]

I have a small issue. I'm trying to resize rows to its content. So in order to do that, I use resizeRowsToContents() method. But something funny is happening. I would like to call this function from a constructor because data won't change anymore so I want to resize them only once. But when I do that, rows are indeed resized but a bit larger than they suppose to be. And when I call this function once again (button click), rows will be resize properly.
So my question is why resizeRowsToContents doesn't work properly when it's called from a constructor?

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    QTableWidgetItem *item;
 
    ui->setupUi(this);
    ui->tableWidget->verticalHeader()->hide();
    ui->tableWidget->insertRow(0);
    item = new QTableWidgetItem("aaa bbb ccc ddd eee fff ggg hhh iii jjj kkk lll mmm nnn ooo ppp");
    ui->tableWidget->setItem(0, 0, item);
    ui->tableWidget->resizeRowsToContents(); // resizes but the row is bigger than a content
}
 
void MainWindow::on_pushButton_clicked() {
    ui->tableWidget->resizeRowsToContents(); // that will resize properly
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    QTableWidgetItem *item;

    ui->setupUi(this);
    ui->tableWidget->verticalHeader()->hide();
    ui->tableWidget->insertRow(0);
    item = new QTableWidgetItem("aaa bbb ccc ddd eee fff ggg hhh iii jjj kkk lll mmm nnn ooo ppp");
    ui->tableWidget->setItem(0, 0, item);
    ui->tableWidget->resizeRowsToContents(); // resizes but the row is bigger than a content
}

void MainWindow::on_pushButton_clicked() {
    ui->tableWidget->resizeRowsToContents(); // that will resize properly
}

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Without resize
table1.png

Resize called from a constructor
table2.png

Resize called from clicked method
table3.png