llDetectedTouchPos returns an TOUCH_INVALID_VECTOR when the viewer is in Mouselook and llDetectedTouchPos is used in touch_start or touch events.
When used in the touch event, the first poll returned will be TOUCH_INVALID_VECTOR, subsequent polls will return a valid value.
Used in touch_start, it will always return TOUCH_INVALID_VECTOR when in Mouselook.
When the viewer is not in Mouselook, the function returns correct values in all events.