gistfile1.txt

bool QGraphicsScene::event(QEvent *event)
{
    Q_D(QGraphicsScene);

    switch (event->type()) {
...

    case QEvent::WindowActivate:
        if (!d->activationRefCount++) {
            if (d->lastActivePanel) {
                // Activate the last panel.
                d->setActivePanelHelper(d->lastActivePanel, true);
            } else if (d->tabFocusFirst && d->tabFocusFirst->isPanel()) {
                // Activate the panel of the first item in the tab focus
                // chain.
                d->setActivePanelHelper(d->tabFocusFirst, true);
            } else {
                // Activate all toplevel items.
                QEvent event(QEvent::WindowActivate);
                foreach (QGraphicsItem *item, items()) {
                    if (item->isVisible() && !item->isPanel() && !item->parentItem())
                        sendEvent(item, &event);
                }
            }
        }
        break;