[UFO Chicago] Creating an api for an exsisting project

[Jeremiah Benham]

I found this project I am interested in. It does not yet have an api. We
want to create an api to load plugins and expand functionality and allow
users to define what plugins or how much bloat they want with it. Its
entirely written in c and is a GTK+ frontend to lilypond. Its kind of
like what LyX is to LaTeX. I know some of you would say just use $EDITOR. I can very well do that. The thing is I am thinking of other people that are frightened to try out *nix because it does not have a things like a musical score editor.  While it does have lilypond and many other typesetting programs based off of LaTeX most musicians have it set in their mind that score editing should be like $PROPRIETARY_EDITOR. 

So what books or websites would you guys recomend? I did some google
searching but will probably just end up looking at some other project
and see how they did it and then do it in a similar fashion I guess. 

Jeremiah