# Preface

This manual describes the Fast Light Tool Kit ("FLTK") version 2.0, a C++ Graphical User Interface (GUI) toolkit for UNIX and Microsoft Windows. 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.

## Copyrights and Trademarks

FLTK is ©1998-2002 by Bill Spitzak and others. Use and distribution of FLTK is governed by the FLTK Library License (which is the GNU Library General Public License with an exception added that allows you to distribute statically-linked programs using the library without providing source code to the program or the library).

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.

## Abbreviations

The following abbreviations are used in this manual:

X11
  The X Window System version 11.
Xlib
  The X Window System interface library.
WIN32
  The Microsoft Windows 32-bit Application Programmer's Interface.