In this chapter, you learned the following:
Most modern programs provide a graphical user interface (GUI) for displaying information and interacting with users. GUIs are built out of widgets, such as buttons, sliders, and text panels; all modern programming languages provide at least one GUI toolkit.
Unlike command-line programs, GUI applications are usually event-driven. In other words, they react to events such as keystrokes and mouse clicks when and as they occur.
Experience shows that GUIs should be built using the model-view-controller pattern. The model is the data being manipulated; the view displays the current state of the data and gathers input from the user, while the controller decides what to do next.
Lambda expressions create functions that have no names. These are often used to define the actions that widgets should take when users provide input, without requiring global variables.
Designing usable GUIs is as challenging a craft as designing software. Being good at the latter doesn’t guarantee that you can do the former, but dozens of good books can help you get started.