template <class BaseClass>
void QWindowsDialogHelperBase<BaseClass>::cleanupThread()
{
    if (m_thread) { // Thread may be running if the dialog failed to close.
        if (m_thread->isRunning())
            m_thread->wait(500);
        if (m_thread->isRunning()) {
            m_thread->terminate();
            m_thread->wait(300);
            if (m_thread->isRunning())
                qCCritical(lcQpaDialogs) <<__FUNCTION__ << "Failed to terminate thread.";
            else
                qCWarning(lcQpaDialogs) << __FUNCTION__ << "Thread terminated.";
        }
        delete m_thread;
        m_thread = nullptr;
    }
}