QLineEdit can't update inside QStackedWidget

[lwz]

if I have initialized widgets in a wrong way , how can it work just fine when adding 3 or 4 widgets?

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Added after 16 minutes:

This a slice of my code

QStackedWidget *TraceConfigDialog::buildStackedWidget()
{
    QStackedWidget *stackedWidget = new QStackedWidget();
    stackedWidget->addWidget(linearGroupBox());
 
    stackedWidget->addWidget(fillingGroupBox());
#if 1     // here if I put this "#if 1" on the 5th line , qlineedit can't update , actually all widgets inside the stacedwidget can't update.
    stackedWidget->addWidget(imageGroupBox());
    stackedWidget->addWidget(textGroupBox());
    stackedWidget->addWidget(logGroupBox());
    stackedWidget->addWidget(waveGroupBox());
    stackedWidget->addWidget(depthGroupBox());
    stackedWidget->addWidget(timeGroupBox());
    stackedWidget->addWidget(tadpoleGroupBox());
#endif 
   return stackedWidget;
}
 
void inti()
{
   vlayout=new QVBoxLayout();
    vlayout->addWidget(listWidget);
    vlayout->addWidget(curveStyleLabel);
    vlayout->addWidget(curveStyle);
 
 
    layout=new QHBoxLayout();
    layout->addLayout(vlayout);
 
    stackedWidget = buildStackedWidget();     // <----
    m_rightLayout = new QVBoxLayout();
    m_rightLayout->addWidget(stackedWidget,10);
 
    layout->addLayout(m_rightLayout);
    layout->addStretch();
 
    widget->setLayout(layout);
}
 
    QPushButton *recommendButton = new QPushButton(tr("Recommend Value"));
    connect(recommendButton,SIGNAL(clicked()),this,SLOT(handleRecommendValue()));
 
void TraceConfigDialog::handleRecommendValue()
{
 
        m_linearLeftValue->setText("testest); // <--- m_linearLeftValue is a QLineEdit
        m_linearLeftValue->update();
        stackedWidget->update();
}

QStackedWidget *TraceConfigDialog::buildStackedWidget()
{
    QStackedWidget *stackedWidget = new QStackedWidget();
    stackedWidget->addWidget(linearGroupBox());

    stackedWidget->addWidget(fillingGroupBox());
#if 1     // here if I put this "#if 1" on the 5th line , qlineedit can't update , actually all widgets inside the stacedwidget can't update.
    stackedWidget->addWidget(imageGroupBox());
    stackedWidget->addWidget(textGroupBox());
    stackedWidget->addWidget(logGroupBox());
    stackedWidget->addWidget(waveGroupBox());
    stackedWidget->addWidget(depthGroupBox());
    stackedWidget->addWidget(timeGroupBox());
    stackedWidget->addWidget(tadpoleGroupBox());
#endif 
   return stackedWidget;
}

void inti()
{
   vlayout=new QVBoxLayout();
    vlayout->addWidget(listWidget);
    vlayout->addWidget(curveStyleLabel);
    vlayout->addWidget(curveStyle);


    layout=new QHBoxLayout();
    layout->addLayout(vlayout);

    stackedWidget = buildStackedWidget();     // <----
    m_rightLayout = new QVBoxLayout();
    m_rightLayout->addWidget(stackedWidget,10);

    layout->addLayout(m_rightLayout);
    layout->addStretch();

    widget->setLayout(layout);
}

    QPushButton *recommendButton = new QPushButton(tr("Recommend Value"));
    connect(recommendButton,SIGNAL(clicked()),this,SLOT(handleRecommendValue()));

void TraceConfigDialog::handleRecommendValue()
{

        m_linearLeftValue->setText("testest); // <--- m_linearLeftValue is a QLineEdit
        m_linearLeftValue->update();
        stackedWidget->update();
}

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The QLineEdit is inside linearGroupBox() , which return a QGroupBox. And there is a QPushButton inside the linearGroupBox()