QDockWidget gets unresizeble if contains QWindow inside

I am developing a windows application that contains dockable widgets. Some of that widgets contains QWindow based widgets. Recently I built my project with Qt 5.10 VC 2015 and since that docks, that contains QWindow based widgets lost their title bars and resize handles, so one cannot resize or move them. This issue disappears when the application built with Qt 5.8.0 VS 2015.
To reproduce the issue put bellow code at the end of the void MainWindow::createDockWindows() in dockwidgets Qt sampe:

dock = new QDockWidget(tr("OpenGL"), this);
QWindow* wnd = new QWindow();
QSurfaceFormat format;

format.setDepthBufferSize(16);
format.setSwapInterval(1);
format.setSwapBehavior(QSurfaceFormat::DoubleBuffer);
format.setRenderableType(QSurfaceFormat::OpenGL);
format.setProfile(QSurfaceFormat::CoreProfile);

wnd->setSurfaceType(QWindow::OpenGLSurface);
wnd->setFormat(format);

wnd->create();
QWidget* cont = QWidget::createWindowContainer(wnd);
dock->setWidget(cont);
addDockWidget(Qt::RightDockWidgetArea, dock);