Analyze a Platform dependent Module written in FreePascal using GTK Libraries

Analyze a platform dependent module (~600 lines of code) written in FreePascal using GTK+ Libraries. Write a Description for each Function/Procedure in the Module, what the Function/Procedure is all about, where to find Information about the Methods used in each Function/Procedure and last but not least make useful comment in the code so further work with the module gets easier. You should have a good knowledge of either FreePascal or Delphi!