GTK+2.0, How to Draw in Window and create a pie chart?

I have a widget called "window" that is a new window created from "gtk_window_new" and I have a signal handler for a button click that I want to have it draw a pie chart on the window. The GTK+2.0 Tutorial is not that clear on how to do this (see the Scribble example). How can I have the signal handler draw a pie chart? I have thought of using "gdk_draw_arc" to make the pie chart. What example code will do this?