A sweet and sentimental tearjerker that bears the stamp of the Disney studio that produced it, The Station Agent is toughened a bit, at the core, by its relentless view of the selfishness of its three main characters—until the end, that is, when, predictably, one comes through big time for one of the other two. A more contrived script would be impossible to imagine, but the writer-director, Thomas McCarthy, attempts to give the direction of his actors an air of casualness and spontaneity. I will leave it to others to decide whether McCarthy is entitled to so ardently manipulate his audience, given that a genuine tragedy is sketched into the background of one of the characters, the accidental death of her child who crashed to the ground from park monkey bars on which he was playing when she turned her eyes away for one second. One thing is for certain:…