I am working on a project to edit the GUI of the Unison File Synchronizer (cis.upenn.edu/~bcpierce/unison)

The problem is, I don't know how to access the source code for the GUI file ... Can somebody pls help me?

The programming language used is Ocaml and the GUI is built with gtk+...

Welcome to LQ!!

You have to download the source code and then open it in an editor. The place that you get the SW should have instructions for how to get the source. The GPL requires that the source code be available, but not that it be easy to find.... If nothing else, search Google using--eg--"unison source code"

I googled and found the source code files. Now I have to figure out how and which to edit!

Thanks pixellany for such a prompt and informative reply!

Depends on what language they are in and what kind of editor you like best.
Any editor will techincally work. You can use Kedit, Gedit, Kate, SCITE. Many have built in support for the most common languages.

Scite has built in support for over a dozen languages but will act much like notepad as an editor. If your not sure what language the source is in I'd recomend ScITE as a starting place.

If you want to be hardcore old school and love memorization you can use VI to do it. Me I'd rather chew my dogs leg off than use VI.

For C/C++ Kdevelop is my favored IDE.

Quanta is my favored web development IDE. So for js, PHP, html and other web languages that is a good choice.

CSSed is good for editing .css files.

If the source code is LISP as much as I hate to I'd recomend Emacs which is very friendly for LISP development.

If the code is using the .QT libs then you'll want QT designer.

Anjunta is another good multi-language IDE that you may want to try.