Building with disabled RTTI fails

When building with RTTI disabled the compilation fails on:
qtmultimedia\src\plugins\wmf\player\mfvideorenderercontrol.cpp:2199

because of QChildEvent childEvent = dynamic_cast<QChildEvent>(event);
wich is normal, but I wonder why such dynamic_cast is left?

I have fixed the issue by checking the QEvent::type() if actually is QChildEvent and then cast it using simple static_cast.