QGLWidget obscuring other widgets on Mac

I have both QTreeWidget and QGraphicsView widgets that I open in a frameless window (Qt::FramelessWindowHint) in a GUI that contains one or more QGLWidgets "viewports" active in the window. These widgets can appear over the top of the QGLWidgets under Windows and Linux, but on the Mac, the QGLWidgets remain at the top of the child widget order.

The QGLWidget is part of a QSplitter that can contain additional QGLWidgets or other "viewport" types. My tests are conducted using the QSplitter in a horizontal-split configuration, with the top half containing the QGLWidget. The Tree/GraphicsView widgets are parented to the main window, and setWindowFlags() using (Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint).

I am using Qt 4.6.1 with the following build line for the Mac:

./configure -fast -cocoa -sdk /Developer/SDKs/MacOSX10.5.sdk -arch "x86 x86_64" -prefix <path> -nomake examples -nomake demos

I have also tested Qt 4.6.2 using the same build line as above, with the same resulting behavior.

I did some additional testing by adding a QPushButton child to the main window that contains the QGLWidgets, and positioned it such that it is half over the QGLWidget. No amount of raising or lowering of widgets prevents the QGLWidget on the Mac from obscuring the QPushButton.