As mentioned in {T29203} render window specific names are used in some classes. {D665} removed most of the cases where a string was used.
Inside the `QmitkSlicesInterpolator` there is still a use of a render window string, inside `QmitkSlicesInterpolator::RunPlaneSuggestion()`: it is used to retrieve a render window for a plane suggestions.
Plane suggestion has been disabled in {T28261} and the whole `QmitkSlicesInterpolator` is currently being refactored.
If we know how the future of the slices interpolator and plane suggestions looks, we need to take care of this part of code to make it work without specific render window name strings.