QGraphicsScene problem/bug

Taken directly from the Qt 4.5.2 documentation, in the Detailed Description of QGraphicsGridLayout:

Code:

---

QGraphicsScene scene;
 QGraphicsWidget *textEdit = scene.addWidget(new QTextEdit);
 QGraphicsWidget *pushButton = scene.addWidget(new QPushButton);
 
 QGraphicsGridLayout *layout = new QGraphicsGridLayout;
 layout->addItem(textEdit, 0, 0);
 layout->addItem(pushButton, 0, 1);
 
 QGraphicsWidget *form = new QGraphicsWidget;
 form->setLayout(layout);
 scene.addItem(form);

---

First problem: I don't see anything if I wrap this in a simple QApplication:

Code:

---

int main()
{
QApplication app();
 
QWidget *widget;
 //the above code, with the first line:
 //QGraphicsScene scene(widget);
widget->show();
return app.exec();
}

---

This structure is really important, but when I try to implement it in my class's constructor, it won't compile. What's wrong here? Thanks!

..you don't see anything because you have to show the scene or set it to your widget, using layouts!

Code:

---

int main()
{
QApplication app();
//the above code
scene.show();
return app.exec();
}

---

It might be worth actually having a QGraphicsView somewhere...