the previous revision does not fix the bug completely, for every function in graphics window that may edit or get information from scene_viewer_array should have test on either scene_viewer_array is valid or NULL as cmgui-wx will delete the scene_viewer_array in that particular graphics window as it closes the graphics window.
the previous revision does not fix the bug completely, for every function in graphics window that may edit or get information from scene_viewer_array should have test on either scene_viewer_array is valid or NULL as cmgui-wx will delete the scene_viewer_array in that particular graphics window as it closes the graphics window.

git-svn-id: 4705079bc6b8aadf675e3696f5c015a6aa4916e3@5590 3c1deb5b-d424-0410-962d-aba41a686d42

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