Abstract: A portable computing device or “information appliance” having terse user input (e.g., limit set of keys) is provided with a user interface for navigating user data. Application programs, which are provided for user operation of the device, are implemented as separate modules controlled by a module selector. The module selector serves as a user interface or shell representing the top-level or “home” display presented to a user. The module selector presents the user with selection icons for navigating to different applications or modules of functionality. The user interface implements a “single-click” style of button operation, so that users can associate each button with a particular task for a given program context. In addition to the single-click style, “click consistency” is imposed for each button.