Steph is a portable C library for text mode windows, menus, dialogs, etc. The interface with the underlying system is provided by a separate library, so to port to a new system, only the interface library needs to be rewritten. Interface libraries are provided for Unix/Curses and IBM PC compatibles running DOS.
Setedit is a text editor specially designed for programmers. It has a nice interface with mouse support, menus and windows (text mode). The editor is a very good choice for people with DOS background, especially people accustomed to Worstar and Borland editors. The editor has overlapped windows so you can see more than one file at the same time, configurable syntax highlighting, macros, rectangular selection, block indentation, as well as customizable keyboard shortcuts and menus.