A method, comprising: at an electronic device having a display and a touch-sensitive surface: displaying a first user interface of a first application on the display; while displaying the first user interface of the first application, detecting a first input by a first contact on the touch-sensitive surface that meets navigation-gesture criteria, wherein the navigation-gesture criteria require that the first input includes a movement of the first contact across the touch-sensitive surface that crosses a boundary of a predefined edge region of the touch-sensitive surface in order for the navigation-gesture criteria to be met; in response to detecting the first input by the first contact that meets the navigation-gesture criteria: in accordance with a determination that the first application is not protected, ceasing to display the first user interface of the first application and displaying a respective other user interface on the display; and in accordance with a determination that the first application is protected, maintaining display of the first user interface of the first application without displaying the respective other user interface; in accordance with a determination that the first application is protected and while display of the first user interface of the first application is maintained in response to detecting the first input by the first contact: after forgoing displaying the respective other user interface in response to detecting the first input by the first contact, and while maintaining display of the first user interface of the first application, detecting a second input by a second contact on the touch-sensitive surface that meets the navigation-gesture criteria; and in response to detecting the second input by the second contact on the touch-sensitive surface that meets the navigation-gesture criteria: in accordance with a determination that the second input is detected within confirmation time threshold of the first input, ceasing to display the first user interface of the first application and displaying the respective other user interface on the display. displaying a first user interface of a first application on the display; while displaying the first user interface of the first application, detecting a first input by a first contact on the touch-sensitive surface that meets navigation-gesture criteria, wherein the navigation-gesture criteria require that the first input includes a movement of the first contact across the touch-sensitive surface that crosses a boundary of a predefined edge region of the touch-sensitive surface in order for the navigation-gesture criteria to be met; in response to detecting the first input by the first contact that meets the navigation-gesture criteria: in accordance with a determination that the first application is not protected, ceasing to display the first user interface of the first application and displaying a respective other user interface on the display; and in accordance with a determination that the first application is protected, maintaining display of the first user interface of the first application without displaying the respective other user interface; in accordance with a determination that the first application is not protected, ceasing to display the first user interface of the first application and displaying a respective other user interface on the display; and in accordance with a determination that the first application is protected, maintaining display of the first user interface of the first application without displaying the respective other user interface; in accordance with a determination that the first application is protected and while display of the first user interface of the first application is maintained in response to detecting the first input by the first contact: after forgoing displaying the respective other user interface in response to detecting the first input by the first contact, and while maintaining display of the first user interface of the first application, detecting a second input by a second contact on the touch-sensitive surface that meets the navigation-gesture criteria; and in response to detecting the second input by the second contact on the touch-sensitive surface that meets the navigation-gesture criteria: in accordance with a determination that the second input is detected within confirmation time threshold of the first input, ceasing to display the first user interface of the first application and displaying the respective other user interface on the display. after forgoing displaying the respective other user interface in response to detecting the first input by the first contact, and while maintaining display of the first user interface of the first application, detecting a second input by a second contact on the touch-sensitive surface that meets the navigation-gesture criteria; and in response to detecting the second input by the second contact on the touch-sensitive surface that meets the navigation-gesture criteria: in accordance with a determination that the second input is detected within confirmation time threshold of the first input, ceasing to display the first user interface of the first application and displaying the respective other user interface on the display.