Cocoa Text System
A very comprehensive overview of the Cocoa text system and how to customize it:
http://hcs.harvard.edu/~jrus/Site/Cocoa%20Text%20System.html
I have had to figure out a lot of this myself when developing JobTimer X (an in-house time keeping tool for Buttgereit und Heidenreich) and Kaleidotype. But this is also the fun in programming – bending the system to your needs.