... A widget is any GtkObject that derives from GtkWidget ; before reading this chapter, you should be familiar with the chapter called The GTK+ Object and Type System . ... You will also need to know something about GDK to write a widget; be sure to skim the chapter called GDK Basics if you haven't. Widgets are easy to create; you only need to cut-and-paste the usual GtkObject boilerplate (instance and class initializers, a get_type() function, and so on), and then implement your widget's functionality...