Main Thread Is Blocked By Mouse Wheel When I Involved other ui process for QT 5.14.2

[even0421]

My application use microsoft webview2 to show webpage, but I found when I use mouse wheel on webview plugin my main thread is blocked so that my application ui is lag.
I also try use createWindowcontainer to create a widget using other process(like notepad), it's same to the webview, is it a bug in QT or I use wrong config?
Please help me, thanks!

[Axel Spoerl]

@even0421
Please provide a minimal, compilable reproducer.
Please also note that Qt 5.14 is no longer supported.

[even0421]

@Axel-Spoerl Thanks for replying! I just wrote a simple example:

QWindow * window = QWindow::fromWinId(5310800);
    if (window)
    {
        window->setFlags(window->flags() | Qt::CustomizeWindowHint | Qt::WindowTitleHint | Qt::WindowDoesNotAcceptFocus); /
        QWidget * widget = QWidget::createWindowContainer(window, this, Qt::Widget);
        widget->resize(300,300);
        layout()->addWidget(widget);
    }

    auto m_timer = new QTimer();
    m_timer->setInterval(40);
    m_timer->setTimerType(Qt::TimerType::PreciseTimer);
    connect(m_timer, &QTimer::timeout, this, [this]() {
        auto currentTime = QDateTime::currentMSecsSinceEpoch();
        if (m_lastTime != 0) {
            qDebug() << currentTime - m_lastTime;
        }
        m_lastTime = currentTime;
    });
    m_timer->start();

when I scroll on window which Hwnd is "5310800"(any program is ok, like calculator), the main thread of my application is blocked, because there is no print of interval in timeout slot.

[Axel Spoerl]

@even0421
I can’t reproduce that with Qt 6.5 on openSuSE Linux.
I haven’t tried on 5.14 and I won’t do that.
Suggest you upgrade to a supported Qt version and try again.