Child widgets not repainted with WA_OpaquePaintEvent set on parent

The attribute WA_OpaquePaintEvent has different behavior in Qt5.3 from previous versions.

Let's say you have a widget that draws a fancy background. It does not need any Qt or system provided background, so it sets WA_OpaquePaintEvent. But it also has one or more child widgets.

In Qt 5.3.0 Beta1, an update() or repaint() on the parent widget does not redraw any of the child widgets. They disappear.

In previous versions, the child widgets would redraw.

I've attached a sample project that illustrates it.

When you run the program, press '0' to repaint the parent (and see the child widgets disappear), or press '1', '2' or '3' to repaint the child widgets.