In order to fix T3204, the application needs to know when slices of render windows are rotated.

Since slice rotation is done by subclasses of mitk::SlicesCoordinator, this class would be the most appropriate one to send notification events.

I would introduce a new mitk::SliceRotationEvent (of type itk::Event) and would send it in appropriate places of mitk::SlicesCoordinator's subclasses mitk::SliceRotator and mitk::SliceSwiveller.

A good test for this is the "Segmentation" bundle, which will observe such events and react with a graphical notice if image and renderwindow slices do not align.