[5.14 Regression] QWebEnginePage Can Fail to Render

When browsing with multiple QWebEngineViews / QWebEnginePages, and one or more of the views have been hidden for ~10-30 seconds, it is very likely that the frame will be lost, and the page can not be rendered without adjusting the size of the viewport, thus forcing a repaint. Generally, around 5 or 6 web views must be active before the issue can be reproduced.

It is strange because the mouse and keyboard can still interact with the unrendered web page - for example, it is possible to click on a link, open a context menu, etc., but otherwise nothing appears on the screen.

If a page is in this state and I attempt to load a new URL in the same QWebEngineView/Page, it will also fail to render, unless I adjust the size of the window or container holding the QWebEngineView.

For now my project is using this uncumbersome hack to fix the rendering issue, although it does not work 100% of the time:

#if (QTWEBENGINECORE_VERSION >= QT_VERSION_CHECK(5, 14, 0))
void WebWidget::showEvent(QShowEvent *event)
{
    const bool updateWebContents = !m_hibernating && m_view && m_page;
    if (updateWebContents)
    {
        if (m_page->lifecycleState() != WebPage::LifecycleState::Active)
            m_page->setLifecycleState(WebPage::LifecycleState::Active);
    }

    QWidget::showEvent(event);

    if (updateWebContents && m_view->getProgress() == 100)
    {
        // Hack to force a frame into the view.
        // With QtWebEngine 5.14 it is possible we could otherwise have a dead/blank frame
        m_view->resize(width(), height() * 9 / 10);
        m_view->show();

        QTimer::singleShot(15, this, [this](){
            if (m_hibernating || !m_view || !m_page)
                return;

            updateGeometry();

            m_view->resize(size());
            m_view->show();
        });
    }
}
#endif

Would this have been caused by the compositor change (https://codereview.qt-project.org/c/qt/qtwebengine/+/246364 )? QtWebEngine 5.13 and prior versions do not have the issue.