When running Steps 4 to 7, only the two 2D views for slicing through the data are displayed, and not the 3D view.
Might be solved specifying the "Stretch" parameter when adding the widgets to the layout:
layout.addWidget(&renderWindow, **1**);
It was tested in the MITK master branch #647640c36bcc` using VS2015 x64 and x32 on a Windows 10 system.