QFrame does not emit leave event when opening dialog from mouseReleaseEvent() when used in popup (menu widget)

void DraftMenuButton::mouseReleaseEvent( QMouseEvent *event )
{
    Q_UNUSED(event);

    QMessageBox draftMessageBox;
    draftMessageBox.setText("Click OK to close me.");
    draftMessageBox.exec();

    // Hover highlight stays in Qt 5, but not reproducible on Qt 4 environment.
    //QTimer::singleShot(0, dialog, SLOT(exec()));
    //QFocusFrame::mouseReleaseEvent(event);

#if USE_WORKAROUND
    // Workaround for Qt 5 environment.
    // The hover state is reset after a leave event sent.
    QEvent e(QEvent::Leave);
    QApplication::sendEvent(this, &e);
#endif
}