Fixed the segfault that was happening when left clicking a view then clicking...

Fixed the segfault that was happening when left clicking a view then clicking the project tree. Fixes #5111

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/branches/ipce@8286 41f8697f-d340-4b68-9986-7bafba869bb8