[Newbies] Halt doesn't stop

Following Squeak + Robots, introducing a 'self halt' statement into a method definition and expecting the program execution to stop and a debug window to open. That window opens but the execution of the method continues, so in the repeating pattern example I end up with three or four small 'pre debug windows' I think they're called, and the pattern is drawn as it would be without any such halt statement. Why wouldn't the program stop execution when the halt statement is reached? That seems to be what the book describes.

-- Sent from: http://forum.world.st/Squeak-Beginners-f107673.html