@ken-martin and VTK core developers: It is a quite serious issue that VTK rendering is incorrect on Intel graphics cards on Windows. We discovered a while ago that core OpenGL profile does not work in VTK render windows in Qt-based applications, but now it seems that pure VTK render windows require compatibility profile, too. A quick workaround would be to enable compatibility profile on Windows (in both QVTK rendering widgets and basic VTK render windows), but the proper solution would be to debug what causes the rendering failure when core profile is used.