1. On a multi-touch display device, a computer-implemented method comprising: defining a first visual display layer for displaying elements on a display component of a multi-touch display device, the multi-touch display device configured to detect multiple concurrent touches on the multi-touch display device; defining a second visual display layer for displaying elements on the display component of the multi-touch display device, the second visual display layer having a different virtual depth relative to a foreground of the display component than a virtual depth of the first visual display layer such that elements assigned to the second visual display layer are displayed at the different virtual depth relative to the foreground of the display component than elements assigned to the first visual display layer; defining a third visual display layer stacked on top of both the first and second visual display layers for displaying a control element on the display component, the control element being actuatable to toggle an operating mode of the multi-touch display between an annotation mode and a manipulation mode, the third display layer having a different virtual depth relative to both the first and second visual display layers, the third visual display layer being located at the foreground of the display component; assigning a first object to the first visual display layer, and establishing relationships between the first object and corresponding positions on the first visual display layer to be maintained when transformations are applied to the first visual display layer; assigning a second object to the second visual display layer, and establishing relationships between the second object and corresponding positions on the second visual display layer to be maintained when transformations are applied to the second visual display layer; displaying, on the display component, the first object at the first visual display layer and the second object at the second visual display layer, wherein the first and second visual layers are stacked on top of one another, and wherein the second object occludes objects with which it overlaps that are assigned to the first visual display layer; determining that an input mechanism engaged a surface of the multi-touch display device at a particular location; determining, based on the particular location, that input received from the input mechanism while the input mechanism remains engaged with the surface of the multi-touch display device is to be assigned to the first visual display layer; monitoring movement of the input mechanism while the input mechanism remains engaged with the surface of the multi-touch display device; determining that the input mechanism has traced a path across the surface of the multi-touch display device; defining an annotation having a shape that follows the determined path traced by the input mechanism; determining that a position of the annotation is related to a position of the first object; in response to determining that the position of the annotation is related to the position of the first object, assigning the annotation to the first visual display layer with a higher order than the first object, and establishing relationships between the annotation and corresponding positions on the first visual display layer to be maintained when transformations are applied to the first visual display layer; and displaying, on the display component, the annotation with the higher order on top of the first object at the first visual display layer.