Trying to detach a widget derived from QGLWidget by setting it's parent to NULL (setParent(NULL)) doesn't create a valid OpenGL window on OS X. After a GLWidget is created detaching a normal QWidget doesn't work anymore either. With Qt 4.8 all of this works just fine.

The example project (DetachTest.zip) has a GLWidget and a normal widget with buttons to create the GLWidget and detach both widgets. Before creating the GLWidget detaching the normal widget works (blue widget shown in detached window). After the GLWidget is created trying to detach either of the widgets results in a white external window. Re-attaching the widgets allows them to be drawn correctly again.

The example runs fine in Qt 4.8, but shows the described problem in both Qt 5.0.1 and the current Qt 5 dev branch.