An electronic device with a touch-sensitive display concurrently displays a first application user interface on a first portion of the display, and a second application user interface on a second portion of the display. The device detects a first input including movement in a first direction. In response, the device, when the first input meets first criteria, replaces display of the first and second user interfaces with a full-screen home screen, and when the first input meets second criteria, and started in a first edge region, replaces display of the first application user interface with a first replacement user interface while maintaining display of the second application user interface, and when the first input meets the second criteria, and started in a second edge region, replaces display of the second application user interface with a second replacement user interface while maintaining display of the first application user interface.