The ornamental design for a stylus for touchscreens, as shown and described.
1. Stylus for touch screens
1.1: Perspective
1.2: Front
1.3: Back
1.4: Left
1.5: Right
1.6: Top
1.7: Bottom
1.8: Reference
The broken lines are for illustrative purposes only and form no part thereof; reproduction no. 1.8is a reference view showing the design in use and form no part of the claimed design; the claimed design is for touch buttons or touch screens of electronic devices.