The pen is inverted.
using UnityEngine;
public class Example : MonoBehaviour { void OnGUI() { Event m_Event = Event.current;
if (m_Event.type == EventType.MouseDown) { if (m_Event.pointerType == PointerType.Pen) //Check if it's a pen event. { if (m_Event.penStatus == PenStatus.Inverted) Debug.Log("The pen is inverted."); } else Debug.Log("Mouse Down."); //If it's not a pen event, it's a mouse event. } } }