The graphical interface to the graph class is built as a standard X application. For our purposes, the relevant code we wish to discuss is the method where we introduce the graph data and format it for graphing and the main simulation function. These details are discussed in Experiments in Object Oriented Design: Simple Beginnings, Version 1.0 http://www.math.clemson.edu/~peterson/Agents/Graph1/index.html. The code to draw a typical graph object is handled in a callback method as discussed in that previous volume.