The Fast Light Tool Kit ("FLTK", pronounced "fulltick") is an LGPL'd GUI toolkit for C++ programs. FLTK supports X11 and WIN32 applications; support for MacOS is under development.
FLTK 1.1.0rc1 is now available for download and is a
candidate for the final 1.1.0 release. Aside from several bug
fixes, this release also contains many enhancements to the FLUID
program and file chooser.