Code

#include <QtWidgets>
#include <QOpenGLWidget>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QMainWindow w;
    w.setCentralWidget(new QOpenGLWidget);
    w.addDockWidget(Qt::LeftDockWidgetArea, new QDockWidget);
    w.menuBar()->addAction("WA_NativeWindow", [&w] {
        w.centralWidget()->setAttribute(Qt::WA_NativeWindow);
        w.menuBar()->setStyleSheet("background: red;");
    });
    w.resize(240, 180);
    w.show();

    return a.exec();
}

Steps to reproduce

1. Build and run the code above
2. Grab the splitter handle and wiggle it rapidly
3. Click the menu item, "WA_NativeWindow"
4. Repeat Step #2

Outcomes
Step 2 is very smooth, but Step #4 is glitchy (see attached video).

Notes

• Qt 6.5.1 is affected by QTBUG-113652 so the patch needs to applied first to see the effect.

• The severity of the glitching seems to be hardware dependent.
  • The customer sees it very strongly on Dell XPS 15 9510, i7-11800H, RTX 3050 Ti, Win11 22H2
  • Not so strong on i9-9900K, Geforce GTX 980, Win10
  • Not so strong on i9-10980XE, Win11 22H2