A graphical user interface for a portable electronic device includes an application display region that displays a current application context of an application and a navigation bar adjacent to the application display region. The navigation bar includes two horizontally adjacent regions, comprising a current context region for displaying an indicator of the current application context and a prior context region for displaying an indicator of an application context preceding the current application context. The application display region simulates shifting of the application display in a first direction upon detecting user selection of the prior context region, and simulates shifting of the application display in a second direction, opposite the first direction, upon detecting user selection of an application context different from the current application context and the prior application context.