Updates: Status: ClosedComment #7 on issue 2611 by stephane.ducasse: DNU when clicking on active text in class comment
http://code.google.com/p/pharo/issues/detail?id=2611
I tried your script and it is empty now on 12286 I also tried ProtoObject allSubclasses do: [:class | (class comment class = Text) ifTrue: [ Transcript cr; show: class] ] and it is empty I guess that the issue is fixed