The ornamental design for a touchscreen, as shown and described.
FIG. 1 is a front view of a touch screen for a dashboard of a vehicle according to the present invention, with the rest of the dashboard shown in de-emphasized and half-tone portions so as to illustrate environmental structure. These portions form no part of the claimed invention. In FIG. 1, the touch screen of the present invention is shown within the broken line, and any elements shown outside of the broken line form no part of the claimed invention, but are instead included to show environmental aspects of the claimed invention.
FIG. 2 is a front left perspective view of the touch screen shown in FIG. 1.