When DDLab is run, the user interface (white background) appears, with a title bar across the bottom of the screen. A series of prompts are presented to set up the network and presentation parameters. These prompts appear either in a main sequence for the most commonly needed settings, or in various windows that automatically open up. If a mouse is detected, a mouse cursor will also appear. It is used to set bits in rule-tables and network states, and for ``drawing'' bit patterns in 2d networks. Otherwise it is just a pointer.