Because QGLView inherits QWindow now (and not QGLWidget as it does before) it can't be used on QDockWidget, QTabWidget, QStackedWidget or any other container widget anymore. (QDockWidget::setWidget() expects a QWidget as parameter). So one possible solution might be to give the container classes overloaded methods to accept QWindow derived classes, e.g.
QDockWidget::setWidget/setWindow(QWindow * window);
QTabWidget::addTab(QWindow * page, const QString & label);
etc.

That might be the same problem as described in
https://bugreports.qt-project.org/browse/QTBUG-25643
but QGLView isn't explicitly mentioned there.