Suggestion for text editing module

["Matthew A. Postiff" <postiffm comcast net>]

Hi,

I have a gtk2 app that is, among other things, an editor for a data
format called USFM. The program can display the data (text) in the
encoded format, or in a pretty format, and the user can edit the data in
either view. The editor is hand-built and somewhat buggy. I was
wondering if you all have any suggestions for a pre-existing text
editor/source code editor module that I could drop into my app, with
some customization, to replace the buggy code?

Here is what the USFM view looks like, with \c = chapter, \p =
paragraph, \v = verse (and many other such content and formatting markers):

\c 6
\p
\v 1 There is an evil which I have seen under the sun, and it is common
among men:
\v 2 A man to whom God has given riches and wealth and honor, so that he
lacks nothing for himself of all he desires; yet God does not give him
power to eat of it, but a foreigner consumes it. This is vanity, and it
is an evil affliction.
\p
\v 3 ...

Here is what the pretty view looks like:

6 (in big print)
1 (superscript) There is an evil which I have seen under the sun, and it
is common among men: 2 (superscript) A man to whom God has given riches
and wealth and honor, so that he lacks nothing for himself of all he
desires; yet God does not give him power to eat of it, but a foreigner
consumes it. This is vanity, and it is an evil affliction.
3 (superscript)...

Thanks for any ideas you throw my way...

Matt