QGLWidget with a child QDockWidget containing a QWebEngineView may result in corrupted graphics

In a very specific setup including QGLWidget as the central widget of a QMainWindow and QWebEngineView inside a QDockWidget as a child of the central widget, the QMainWindow separator may get drawn entirely black despite being set green with a stylesheet.

This seems to occur exclusively with QGLWidget. The separator would be drawn correctly as green if QGLWidget is replaced with any other widget (including QOpenGLWidget).

Machines affected by the issue have the separator drawn consistently as black while on some machines the problem does not appear at all.

Application output on an affected machine:

Attribute Qt::AA_ShareOpenGLContexts must be set before QCoreApplication is
created.
QWindowsGLContext::makeCurrent: SetPixelFormat() failed (Unknown error
0xc0070006.)
qt.qpa.backingstore: composeAndFlush: makeCurrent() failed
QWindowsGLContext::makeCurrent: SetPixelFormat() failed (Unknown error
0xc0070006.)
qt.qpa.backingstore: composeAndFlush: makeCurrent() failed

**The problem can be reproduced on some machines by running the attached example. More information on the machine able reproduce the issue in qtdiag.txt