A strange bug?

Comparing the DotView example in ASOC and Objective C explained on bynkii.com, I’ve done this test :

In ASOC, Comment the mouseUp function, Clean all targets, Build and Run : ok, the dot doesn’t move.
(Without cleaning targets, mouseUp is still enabled in ASOC while being commented, not with Objective C).
Then, Uncomment the mouseUp function, Clean all targets, Build and Run : the dot cannot move anymore.
It’s not the case with Objective C…