I am not quite sure about the "ABC" format.
Is this the same as the free "LilyPond" score rendering project uses?
The final score renderings look awesome but it does not come with a graphic editor and is somewhat unpleasing to use...
Anyway, if people like to try it for printing "ABC", you can find "LilyPond" here:
http://lilypond.org/index.de.html