Steps to reproduce crash:

1. load an image (I used Pic3d.nrrd)
2. open segmentation view
3. create a segmentation (don't use add, regiongrowing, etc.)
4. close segmentation view
5. select segmentation in datamanager
6. open segmentation view
7. choose an editing tool (eg. add)
8. try to paint in the picture
9. select your picture, then again the segmentation
10. choose again an editing tool and paint in the picture
11. close segmentation view
12. it crashes now by reopening the view, while the segmentation in the datamanager is selected