Need to remove the gt_element_group callback when the scene_object is destroyed.
Need to remove the gt_element_group callback when the scene_object is
destroyed.


git-svn-id: 4705079bc6b8aadf675e3696f5c015a6aa4916e3@2276 3c1deb5b-d424-0410-962d-aba41a686d42

hsorby/zinc,OpenCMISS/zinc,hsorby/zinc,OpenCMISS/zinc,OpenCMISS/zinc,OpenCMISS/zinc,hsorby/zinc,hsorby/zinc