QProgressDialog: LanguageChange event has no effect on cancel button text

    class QTestTranslator : public QTranslator
    {
        const QString m_str;
    public:
         explicit QTestTranslator(QString m_str) : m_str(qMove(m_str)) {}
         QString translate(const char *, const char *sourceText, const char *, int) const Q_DECL_OVERRIDE
         { return m_str + sourceText + m_str; }
         bool isEmpty() const Q_DECL_OVERRIDE { return false; }
    };

    template <typename Translator>
    class QTranslatorGuard {
        Translator t;
    public:
        template <typename Arg>
        explicit QTranslatorGuard(Arg a) : t(qMove(a))
        { qApp->installTranslator(&t); }
        ~QTranslatorGuard()
        { qApp->removeTranslator(&t); }
    };

    QProgressDialog dlg;
    QPushButton *btn = dlg.findChild<QPushButton*>();
    QVERIFY(btn);
    const QString xxx = QStringLiteral("xxx");
    const QString yyy = QStringLiteral("yyy");
    {
        QTranslatorGuard<QTestTranslator> guard(xxx);
        {
            QPushButton *btn = dlg.findChild<QPushButton*>();
            QVERIFY(btn);
            QTRY_COMPARE(btn->text(), QProgressDialog::tr("Cancel"));
            QVERIFY(btn->text().startsWith(xxx));
        }
    }
    QVERIFY(btn);
    QTRY_COMPARE(btn->text(), QProgressDialog::tr("Cancel"));
    QVERIFY(!btn->text().startsWith(xxx));