if (modifier == Modifier.NoneAllowed)
return
!(Input.GetKey(KeyCode.LeftAlt) ||
Input.GetKey(KeyCode.RightAlt) ||
Input.GetKey(KeyCode.LeftControl) ||
Input.GetKey(KeyCode.RightControl) ||
Input.GetKey(KeyCode.LeftShift) ||
Input.GetKey(KeyCode.RightShift));