The most common method of "breakpointing" is to modify the code you are working on and include a self halt in the right place. Sometimes, however, you find you have a looping operation or some kind of recursive operation and you only want to stop one time. This enhancement provides methods on the class Object enabling these new techniques.
See http://squeak.preeminent.org for details on use.
NOTE: This code is now included in the standard Squeak distribution since v3.9