The Fast Light Tool Kit ("FLTK", pronounced "fulltick") is a a cross-platform 
C++ GUI toolkit for UNIX(r)/Linux(r) (X11), Microsoft(r) Windows(r), and 
MacOS(r) X.  FLTK provides modern GUI functionality without the bloat and 
supports 3D graphics via OpenGL(r) and its built-in GLUT emulation.  It was 
originally developed by Mr. Bill Spitzak and is currently maintained by a 
small group of developers across the world with a central repository in the US.

This is 1.3.x (in development) series.

CAVEATS:
1) fltk13 can be installed alongside fltk (1.1.x), but in order to build it,
you need to remove fltk first (with removepkg); you can then reinstall it
afterwards.
2) In order to avoid conflicting files and some other problems, the homonyms
are renamed, and library and include directories are moved to nonstandard
locations (<libdir>/fltk13/ and /usr/include/fltk13/FL).

If you want cairo support, you need to pass CAIRO=1 to the build script.