The widget won't scroll in QListWidget (via setItemWidget() )

[diro]

Hi all,
I design a custom widget(named MyPanel) inheritanced QWidget, and I add a QListWidget inside it. The QListWidget works well, but if I try to replace the text with a custom widget via setItemWidget(), it looks well, but the scrolling is failed (The custom widgets won't scroll..)

If I create the MyPanel object, it works:
MyPanel panel;
panel.show() // The custom widget and scrollbar works well.

But if I create the MyPanel inside another QWidget, it fails:

class BigPanel:QDialog
{
...
MyPanel *panel = new MyPanel(this);
QVBoxLayout* layout_v = new QVBoxLayout(this);
setLayout(layout_v);
layout_v->addWidget(panel, 0, Qt::AlignCenter);
...
}

Does anybody have idea on it? Thanks~

---

Added after 1 45 minutes:

According to my test, I found that if I add the BigPanel into the QGraphicsScene by QGraphicsScene::addWidget(), it will fail. So I guess it may due to the event propagation issue.