1. Activate the option "C++ -> Qt Class Generation -> Use Qt Module Name in #include directive"
2. Create a new Qt Designer Form Class via "File -> New File Or Project -> Qt -> Qt Designer Form Class"
The generated header file includes QWidget as <QtGui/QWidget> instead of <QtWidgets/QWidget> even though Qt4 is not even installed.
When in addition I activate the option "Add Qt Version #ifdef for module names", the code does not compile since QT_VERSION is of course not defined at that point. The generated modules names on the other hand are correct.