QMdiArea: alien widget shines through QGLWidget

Consider the following example:

#include <QtGui>
#include <QtOpenGL>

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

QMainWindow mainWin;
QMdiArea *mdiArea = new QMdiArea;
mainWin.setCentralWidget(mdiArea);
mainWin.show();

QGraphicsView *glview = 0;

for (int i = 0; i < 3; ++i)

{ QGraphicsView *view = new QGraphicsView; QGraphicsScene *scene = new QGraphicsScene; scene->setBackgroundBrush(QColor(qrand() % 255, qrand() % 255, qrand() % 255)); scene->setSceneRect(QRectF(0.0, 0.0, 256, 256)); view->setScene(scene); mdiArea->addSubWindow(view); view->show(); if (i == 2) glview = view; }

mdiArea->cascadeSubWindows();

if (glview)
glview->setViewport(new QGLWidget);

return app.exec();
}

The expected result is that all sub-windows in the MDI area are shown cascaded without any garbled pixels.

The actual result is that there are garbled pixels in the sub-window with the QGLWidget. The middle sub-window seems to "shine" through the QGLWidget.

The problem seems to be related to mixing alien and native widgets in a QMdiArea.

Note that the problem does not occur if the AA_NativeWindows attribute is set on the QApplication object.