Device, Method, and Graphical User Interface for Managing User Interface Content and User Interface Elements

Alignment guides configured for velocity-sensitive behavior are disclosed. In one embodiment, during a user interface element move gesture, the gesture velocity is determined, and while moving the user interface element during the gesture, the user interface operates in a first or a second state with respect to displaying alignment guides. When the velocity of the user gesture exceeds a predefined velocity threshold, the display of the user interface is maintained in the first state, which does not include visibly displaying alignment guides. When the velocity of the user gesture is less than the predefined velocity threshold, the user interface is displayed in a second state that includes visibly displaying one or more alignment guides. In some embodiments, gesture velocity is used to set alignment guide attraction strength.