diff --git a/thermopi/screen.py b/thermopi/screen.py
index aaf9e3f..f136aad 100644
--- a/thermopi/screen.py
+++ b/thermopi/screen.py
@@ -92,6 +92,8 @@ def main(windowed_mode):
             speed_coeff = math.cos((mouse_angle - (0.5 * PI)) - diff_angle)
             final_speed = movement_speed * speed_coeff
             dial.move_dial(final_speed / -3000.0)
+            pygame.draw.circle(window, (0, 255, 0), (10, 10), 15)
+            pygame.display.flip()
 
 
     pygame.quit()