16. Graphical User Interfaces
“Computing is not aboutcomputers any more.It is about living.”
A graphical user interface (GUI) allows a user to interact with a program by pressing buttons, selecting from menus, entering data in various ways, and displaying textual and graphical entities on a screen. That’s what we are used to when we interact with our computers and with websites. In this chapter, we show the basics of how code can be written to define and control a GUI application. In particular, we show how to write code that interacts with entities on the screen using callbacks. Our GUI facilities are built “on top of” system facilities. The low-level features and interfaces are presented in Appendix E, which uses features ...