FLTK 1.3.4

This manual describes the Fast Light Tool Kit ("FLTK") version 1.3.4, a C++ Graphical User Interface ("GUI") toolkit for UNIX, Microsoft Windows and Apple OS X.

Each of the chapters in this manual is designed as a tutorial for using FLTK, while the appendices provide a convenient reference for all FLTK widgets, functions, and operating system interfaces.

This manual may be printed, modified, and/or used under the terms of the FLTK license provided in Software License.


This manual is organized into the following chapters and appendices:


This manual was generated using Doxygen (see http://www.doxygen.org/) to process the source code itself, special comments in the code, and additional documentation files. In general, Doxygen recognizes and denotes the following entities as shown:

Other code samples and commands are shown in regular courier type.


The following abbreviations are used in this manual:

The X Window System version 11.
The X Window System interface library.
MS Windows, WIN32
The Microsoft Windows Application Programmer's Interface for Windows 2000, Windows XP, Windows Vista, and Windows 7. FLTK uses the preprocessor definition WIN32 for the 32 bit and 64 bit MS Windows API.
The Apple desktop operating sytem OS X 10.0 and later. MacOS 8 and 9 support was dropped after FLTK 1.0.10. FLTK uses the preprocessor definition __APPLE__ for OS X.

Copyrights and Trademarks

FLTK is Copyright 1998-2016 by Bill Spitzak and others. Use and distribution of FLTK is governed by the GNU Library General Public License with 4 exceptions, located in Software License.

UNIX is a registered trademark of the X Open Group, Inc. Microsoft and Windows are registered trademarks of Microsoft Corporation. OpenGL is a registered trademark of Silicon Graphics, Inc. Apple, Macintosh, MacOS, and Mac OS X are registered trademarks of Apple Computer, Inc.

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