In general this might be a problem also for other views because closing the workbench removes the render window part listener: m_RenderWindowListeners.remove(renderWindowListener) in QmitkViewCoordinator::PartClosed. This leads to the issue that the Segmentation view does not listen to the render window part being closed anymore.
Thus in the current scenario the render window part is NOT set to nullptr in the Segmentation view and in turn an invalid access is made when destroying the Segmentation view.

{D743} has been abandoned. Future work can use the the pushed branch as a baseline for a new context menu actions interface.
This was all started in the context of creating a new context menu that can be used elsewhere (not only in the datamanager). Now that T29025: Preference service (access) based on cpp microservices has been resolved we can start working on the parent task as well.

This is not solved with {D795}, right? I can still see slicer->GetRenderer() in line 926, so the render window is still retrieved from the slice navigation controller, which requires the getter to be available in the slice navigation controller.

I rebased this to the latest develop and pushed new branch to rMITK MITK: feature/T25057-Clean-IContextMenuActions for someone else to take over.

@floca Part of this task is done with landing the related diff, introducing the new crosshair-data.

Updated task description since the class has been refactored. However, the issue still exists, but now it is - as far as I can see - only abut getting the visibility etc. which can easily be refactored.

I uploaded a fix in D783. Let's see if this will solve the issue also for Ubuntu.

I tested this on Windows with 4974a335ada8a85d7fba8d313e2efc20acc84b48, which was the latest develop I had, since I recently merged something into develop and couldn't reproduce the error.
Used StdMultiWidget, no other plugins open, no data loaded, only the widget planes available in the data storage.
I tested this with the commit given in the task description and couldn't reproduce the error there as well.

With the child task T29335: [Segmentation] Show interactive warning for uninitialized render window geometry being closed, I will close this task as well. If more plugins should be able to enable blocked render windows, this should now be easily doable.

Pushed new branch to rMITK MITK: feature/T28578-Test-MxN-installer.

Deleted branch from rMITK MITK: feature/T29297-Use-selection-widgets-in-render-window-utility.