A method includes displaying a user interface of an application on a device's touch-sensitive display. The user interface includes a plurality of regions, including a respective region at a respective hierarchy level. The respective region has two or more child regions at a hierarchy level below the respective hierarchy level. The method includes detecting a first contact at a location that corresponds to the respective region and that does not correspond to any of the two or more child regions. When the application is configured to process the first contact, not in conjunction with the respective region, but in conjunction with at least one child region of the two or more child regions, the method includes identifying a respective child region in accordance with positions of the child regions relative to the location, and processing the first contact in conjunction with the identified respective child region using the application.