Rename GetRenderWindow and all similar methods (e.g. GetRenderWindows() and GetActiveRenderWindow()) to GetQmitkRenderWindow, since a QmitkRenderWindow is returned and we have many other RenderWindows (e.g. mitkRenderWindow, vtkRenderWindow, mitkBaseRenderWindow, etc.), which is very confusing for programmers.
Calls like this are very unfortunate:
GettRenderWindowPart()->GetRenderWindow("3d")->GetRenderWindow()