A multi-posix-platform abstraction layer for creating desktop apps
Detroit is a multi-posix-platform abstraction layer for creating portable desktop applications. Detroit offers simple widgets, even more simpler menu system and extensible DSL language in the core.
Curses++ is a set of C++ wrapper classes for the curses library. The project is aimed at providing a layer compatible with any version of curses (ncurses and pdcurses are seen as two major versions) and to be easy-to-use, using familiar STL interfaces.
Coypu is an abstract layer, graphic widgets implementation. It is written in C and is highly portable to most architectures and software/hardware backends (X11, Directfb, GLUT, SDL, WIN32). Being fast and light, it's mainly targeted at embedded devices.