[Pharo-project] How to handle Squeak / Pharo differences

Hi, I've tried to load Koans ( https://www.hpi.uni-potsdam.de/hirschfeld/trac/SqueakCommunityProjects/wiki/...) on Pharo. In KoanInterface>>progressHeight ^Preferences standardButtonFont height + 25 but Preferences is removed from Pharo. Which project can I look at to see how to handle common Squeak / Pharo incompatibilities ? Cheers, Laurent