What if someone like Mary Woodward and her friends shouted to the President and both he and Jackie turned and smiled and waved?
Wrong side of the street.
Woodward and her friends were standing on the north side of Elm Street (i.e., to JFK's right).
JFK temporarily stopped waving before he came to Woodward and Co. and turned his head quickly to his left at Z-143.
Jackie turned her head, in an accelerating manner, to her left at Z-143.5, and had a concerned look on her face when Robert Croft photographed her at Z-161.
At Z-150, Connally turned his head quickly to his left, and was therefore captured "looking straight ahead" in the Croft photo.
Nice try, though.