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Issue 6518: SystemChangeNotifier - cleanup step 4
http://code.google.com/p/pharo/issues/detail?id=6518
Issue 6524: StartupPreferences loads non-Smalltalk files
http://code.google.com/p/pharo/issues/detail?id=6524
Issue 6528: GroupAnnouncer announcer DNU
http://code.google.com/p/pharo/issues/detail?id=6528
Issue 6529: Method changes not picked up by MC Browser
http://code.google.com/p/pharo/issues/detail?id=6529