1. A portable electronic device, comprising: a touch-sensitive display, the touch-sensitive display configured to separately display a plurality of hierarchically ordered user interface screens within a single application, the hierarchically ordered user interface screens including a first predefined user interface screen and a second predefined user interface screen with one or more user interface screens in the hierarchically ordered user interface screens in a plurality of user selectable paths between the first predefined user interface screen and the second predefined user interface screen; one or more processors; memory; and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for: displaying a third user interface screen in the plurality of user interface screens, the third user interface screen belonging to a selected path in the hierarchically ordered user interface screens and being between the first predefined user interface screen and the second predefined user interface screen; detecting a finger gesture on the touch-sensitive display while displaying the third user interface screen; in response to detecting the finger gesture on the touch-sensitive display: replacing display of the third user interface screen with display of the first predefined user interface screen when the detected finger gesture is a two-finger swipe gesture in a first direction; replacing display of the third user interface screen with display of the second predefined user interface screen when the detected finger gesture is a two-finger swipe gesture in a direction that is opposite the first direction; displaying the first predefined user interface screen; detecting a two-finger swipe gesture in the direction that is opposite the first direction on the touch-sensitive display while displaying the first predefined user interface screen; in response to detecting the two-finger swipe gesture in the direction that is opposite the first direction while displaying the first predefined user interface screen, replacing display of the first predefined user interface screen with display of the second predefined user interface screen; displaying the second predefined user interface screen; detecting a two-finger swipe gesture in the first direction on the touch-sensitive display while displaying the second predefined user interface screen; in response to detecting the two-finger swipe gesture in the first direction while displaying the second predefined user interface screen, replacing display of the second predefined user interface screen with display of the first predefined user interface screen; and in response to detecting a single-finger swipe gesture while displaying the second predefined user interface screen, replacing display of the second predefined user interface screen with display of a fourth user interface screen by navigating sequentially to the selected path.