Part III introduces Tk, the toolkit for building graphical user interfaces. The Tcl command interface to Tk makes it quick and easy to build powerful user interfaces. Tk is portable and your user interface code can work unchanged on UNIX, Windows, and the Macintosh.
Chapter 21 describes the basic concepts of Tk and provides an overview of its facilities.
Chapter 22 illustrates Tk with three example programs including a browser for the examples from this book. These examples use facilities that are described in more detail in later chapters.
Geometry managers implement the layout of a user interface. Chapters Chapter 23, Chapter 24, and Chapter 25 describe the pack, grid, and place geometry managers. The packer and gridder are general-purpose managers that use constraints to create flexible layouts with a small amount of code. The placer is a special purpose geometry manager that can be used for special effects.
Chapter 26 describes event bindings that associate Tcl commands with events like keystrokes and mouse motion.
