I may be contradicting my previous post, but my problem is not your
problem. There is a whole class of software that does what you are
are trying to do. This class of software is called text editors. If you have the where-with-all (I don't) you might want to look into
playing around with the source code of an open-source editors.

Also why just mess with a flat file DB when there are open-source
RDBMS you could use?

Good luck with your project!