a C++ widget library built on GLUT
The application programming interface (API) of gltk is taken from gtkmm. It aims to stay compatible with gtkmm for the most commonly used part. It is object-oriented, extensible using inheritance and overrides. And, it uses the signal-slot API of libsigc++ for communication between codes.
The gltk namespace encloses the entire widget library. While the sigc namespace packs a small poor man's substitute of libsigc++. The later can be replaced with the real libsigc++ when available to gain flexibility and performance.