This chapter was a real rollercoaster ride as we went into the depths of PySide programming. We started with discussing event handlers and reimplementation techniques to achieve the task at hand. We also discussed event filters and reimplementing the notify() function. Unless absolutely necessary, the latter forms of reimplementing events should be avoided to make an efficient program.

We then explored a very fundamental mechanism of Qt, signals and slots. The signals and slots mechanism follows an observer pattern listening and binding to objects when called. We started with implementing the built-in signals and slots. Later in this section, we implemented and emitted our own custom signals and also discussed how to listen to them.

In the latter half, we shifted our focus to diagrams and graphics. Starting with the drag and drop functionality usage, we also saw various types of QPainter draw objects. The chapter ended with a brief discussion on graphics and effects. The examples that are shown in the latter half of the chapter are very basic examples to help you understand the basic concepts. Much more complex applications can be designed, and this would by itself be the subject matter for a complete book. In the next chapter, we will learn about using dialogs and widgets to build a complete and usable GUI application.