Here's the source for my cat NLS Editor. It works under Windows. It opens under Unix, but the screenlayout under Unix is bad.
Just one hint: NEVER edit your original file. Work always on a copy !
http://www.schrievkrom.de/uk/tips/downl ... 01-1-0.zip
Just load the configuration map included in the archive and after loading all that stuff one should have a new menu entry in the submenu "Tools".
If I've time I'll correct the Unix problems and write also some documentation for that ....