I have a small MacRuby/HotCocoa application that uses the on_notification method described by Richard Kilmer in his post of Sept 19 2008 http://lists.macosforge.org/pipermail/macruby-devel/2008-September/000539.ht... This application worked well under MacRuby 0.4 and Mac OS 10.5. It intercepts Spotify Growl messages to obtain track title and artist information to pass into an AppleScript Studio application I wrote. The MacRuby/HotCocoa app was provided by a friendly software developer, Peter MacRobert, for me since ASS did not have the appropriate inter-process message handling capability. I upgraded to Snow Leopard and discovered that the app crashed out with MacRuby 0.4. I succeeded in downloading and installing MacRuby 0.5 and now the app loads successfully with no error messages as before under Leopard. Unfortunately the on_notification code does not get triggered any longer. No error messages, just stubbornly refuses to respond when the Distributed Notifications Center gets the Spotify message. I am able to see that the message is there by firing up Growl which shows the message each time Spotify plays a track. I'm looking for guidance if anybody has any words of wisdom please? Has something changed under MacOS 10.6.1 to do with the Distributed Notifications Center or is it likely that my re-installation of MacRuby 0.5 is incorrect and I have to do something additional to get the on_notification method re-enabled? My googling efforts suggest that there are changes in inter-process security with Snow Leopard but I am unable to discover any security violation error messages. Regards Trevor Hills