undesirable transparent cascaded menus

[philw]

Some of our menus are becoming partially or totally transparent after a little use. That is, they are initially correctly opaque, but then at some point become transparent. This is a problem only on Windows XP (SP3) (and not on Solaris). We're using Qt 4.4.3. See attached images.

We're not doing anything special to the QMenu objects. Submenus are created with QMenu::addMenu (const QString& title), and QMenu::addAction (QAction*).

The transparency applies to both the menu background and the foreground menu action text.

Does anyone have any ideas about what might cause this?
Thanks in advance.

[philw]

More info: This _appears_ to possibly be due to a malfunction of an intended feature: popup menus gradually (but quickly) FADE-IN. Possibly, the fading-in DOESN'T COMPLETE.

I don't see any way of disabling the fading-in behavior in code. Is there?

Also, we had thought that maybe we were seeing this bug only in Visual Studio (we're using VS 2008). But actually, we see it also in a release (non-debug) build running outside of visual studio.

This is with Qt 4.4.3 on Windows. (We're on Windows XP SP3).