Its been noted before there may be some leak in Nautilus. I bumped into a possible symptom... 1. Open fresh image (e.g. 50216) 2. Open Transcript. 3. Open *one* System Browser 4. Add instrumentation to method Nautilus >>> NautilusUI >> methodModified: e.g.... Transcript crShow: '>>>' , thisContext printString; tab; show: anAnnouncement printString ; tab ; show: sourceTextModel text. 5. In same System Browser, add method MyPackage >>> MyClass >> test1 Observe steps (4.) and (5.) each logged a single item to Transcript. 6. Open a *second* System Browser and add method MyPackage >>> MyClass >> test2 Observe step (6.) logged two items to Transcript, one for each open System Browser. 7. Close *second* System Browser. 8. In *first* System Browser, modify #test1. Observe step (8.) logged two items to Transcript. I would expect only one. Is there any issue open for this? I couldn't find one. ----------------- Try 1, not sure yet if this is all that is required, but its a start... NautilusWindow >> delete | mod | mod := self model. super delete. ">>>" SystemAnnouncer uniqueInstance unsubscribe: mod. "<<<added" mod ifNotNil: [ mod announce: (WindowClosed new window: self) ] cheers -ben