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.

If you want to disable cairo support, you need to pass CAIRO=0 to the build
script.