I too have this problem.
I am porting my windows screensaver ( http://starmessagesoftware.com/moonscreensaver/ )
to MAC and the function dealloc is not always called:
-dealloc is called when the screen saver was instantiated by SSystem Preferences;
-dealloc is not called when ScreenSaverEngine runs the saver.

I never had such inconsistency problems when working with the screensaver messages on the windows platform.
Everything is rational and systematic on windows' API.

--- SoupGate-Win32 v1.05
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