[Qt-interest] How to fix the crash problem when using QGraphicsView on QMainWindow with QLineEdit

[Steven Chang]

Dear Sir,

I created a QLineEdit in QMainWindow class as below:

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    lineEdit = new QLineEdit(this);
}

Then I created a QGraphicsView and QGraphicsScene in main.cpp and set
MainWindow as the view widget.

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    QGraphicsScene gScene;
    gScene.addWidget(&w);
    QGraphicsView gView;
    gView.setScene(&gScene);
    gView.adjustSize();
    gView.show();
    return a.exec();
}

But after built the App and executed it, the App would crash if I type any
character in lineEdit.
How do I fix this problem?

Best Regards,
Steven