Comment #2 on issue 1044 by v.blonde...@gmail.com: Can't debug block local variables in GT debugger http://code.google.com/p/moose-technology/issues/detail?id=1044
I think so. Because the block in the ifTrue: is inlined at the compilation...
ifTrue: alternativeBlock "Answer the value of alternativeBlock. Execution does not actually reach here because the expression is compiled in-line."
^alternativeBlock value
So the block doesn't exists really at debugging time.