1. An electronic device comprising: a display screen configured to display a graphical user interface that includes a first user interface control displayed at a first position in the graphical user interface and a second user interface control displayed at a second position in the graphical user interface, the second position in the graphical user interface being different than the first position in the graphical user interface; a camera oriented to capture images across a tangible surface of the display screen; an illuminator configured to illuminate a part of the tangible surface; and a processing unit configured to perform operations comprising: accessing an image captured by the camera; identifying multiple regions that are defined within a field of view of the camera and that each correspond to one interface control positioned on the tangible surface; determining, from among the multiple defined regions, a region in which an object detected within the accessed image is positioned, including: determining whether an object is present within a first region of the image that corresponds to the first user interface control, and determining whether an object is present within a second region of the image that corresponds to the second user interface control; determining user input based on the one interface control that corresponds to the determined region and the part of the tangible surface illuminated by the illuminator; and controlling an application based on the determined user input; wherein determining user input based on the one interface control that corresponds to the determined region and controlling an application based on the determined user input comprises: in response to a determination that an object is present within the first region of the image, detecting activation of the first user interface control and triggering a first operation associated with activation of the first user interface control; and in response to a determination that an object is present within the second region of the image, detecting activation of the second user interface control and triggering a second operation associated with activation of the second user interface control.