Introduction to FLTK

FLTK (pronounced "fulltick") is a cross-platform C++ GUI toolkit. FLTK provides modern GUI functionality and supports 3D graphics via OpenGL and its built-in GLUT emulation libraries used for creating graphical user interfaces for applications.

This package is known to build and work properly using an LFS 12.1 platform.

Package Information

FLTK Dependencies


Xorg Libraries



alsa-lib-1.2.11, desktop-file-utils-0.27, Doxygen-1.10.0, GLU-9.0.3, Mesa-24.0.1, and texlive-20230313 (or install-tl-unx)

Installation of FLTK



The tar extraction directory is fltk-1.3.9 and not fltk-1.3.9-source as indicated by the tarball name.

Install FLTK by running the following commands:

sed -i -e '/cat./d' documentation/Makefile       &&

./configure --prefix=/usr    \
            --enable-shared  &&

If you wish to create the API documentation, issue:

make -C documentation html

The tests for the package are interactive. To execute the tests, run test/unittests. In addition, there are 70 other executable test programs in the test directory that can be run individually.

Now, as the root user:

make docdir=/usr/share/doc/fltk-1.3.9 install

If desired, install some example games built as a part of the tests, extra documentation and example programs. As the root user:

make -C test          docdir=/usr/share/doc/fltk-1.3.9 install-linux &&
make -C documentation docdir=/usr/share/doc/fltk-1.3.9 install-linux

Command Explanations

sed ... documentation/Makefile: Avoid installing pages in /usr/share/man/cat*.


Installed Programs: blocks, checkers, fltk-config, fluid, and sudoku
Installed Libraries: libfltk.{a,so}, libfltk_forms.{a,so}, libfltk_gl.{a,so}, and libfltk_images.{a,so}
Installed Directories: /usr/include/FL and /usr/share/doc/fltk-1.3.9

Short Descriptions


is a FLTK-based block elimination game


is a FLTK-based version of the game of checkers


is a utility script that can be used to get information about the current version of FLTK that is installed on the system


is an interactive GUI designer for FLTK


is an implementation of the popular Sudoku game


contains functions that provide an API to implement graphical user interfaces