A method performed at an electronic device with a utility for prototyping a user interface having one or more layers includes, in the utility: for each image of one or more images in the user interface, selecting an image patch, selecting a layer patch, and coupling an image output of the image patch to an image input of the layer patch; selecting a gesture patch and specifying a gesture for the gesture patch; coupling an output of the gesture patch to an input of a first layer patch; generating the user interface for display in accordance with the couplings; receiving user-interaction data for manipulating the user interface, the user-interaction data corresponding to the gesture; and in response to the user-interaction data, updating display of the user interface in accordance with the user-interaction data and the gesture patch as coupled to the first layer patch.