Oswald in the doorway: the blog of the Oswald Innocence Campaign, by Ralph Cinque

Hey Unger! You missed the most important point. It is that the Fedora Man is facing Oswald. 

That circled area between the Woman and Boy is exactly the same tone and darkness as the rest of the jacket. It's all one continuous uninterrupted expanse of material. That's what you have in back, not in front. If that were his front, we'd be seeing some contrast there. So, that man has got his back to us, which is to say, his back to Kennedy. Who would be more interested in looking at Lee Harvey Oswald in the doorway than in President Kennedy as he rode by? There is only one man who comes to mind: Jack Ruby.