Just a curiousity. I learnt something new today... #ifCurtailed blocks are processed in the outer most thread. Transcript clear; crShow: Processor activeProcess; show:' - outside'. p1 := [ [ Transcript crShow: Processor activeProcess; show: ' - inside'. 1 second wait. ] ifCurtailed: [ Transcript crShow: Processor activeProcess; show: ' - curtailed' . ] ] newProcess priority: 41. p1 resume. p1 terminate. ==> a Process(304957184) in nil - outside a Process(680396800) in nil - inside a Process(304957184) in nil - curtailed This makes some sense since (I guess) the inside thread is terminated before the curtailed block executes. However another curiousity... Transcript clear; crShow: Processor activeProcess; show:' - outside'. p1 := [ Transcript crShow: Processor activeProcess; show: ' - middle'. p2 := [ [ Transcript crShow: Processor activeProcess; show: ' - inside'. 1 second wait. ] ifCurtailed: [ Transcript crShow: Processor activeProcess; show: ' - curtailed' . 2 seconds wait ] ] fork. 3 second wait. ] newProcess priority: 41. p1 resume. p2 terminate. ==> a Process(304957184) in nil - outside a Process(146580480) in nil - middle a Process(417340928) in nil - inside a Process(304957184) in nil - curtailed ...why does the curtailed block execute in outside thread rather than the middle thread which still exists? Also interesting is that if the curtailed code contains a wait, it blocks the whole UI. cheers -ben btw, I added... Process>>printOn: aStream super printOn: aStream. aStream nextPutAll: '(' , self hash printString , ') in '. suspendedContext printOn: aStream