'My Old Lady" will hold an enormous fascination for real-estate agents and homeowners over 40, but a sizable portion of the movie-going populace would perhaps miss the point of the story — and do so willingly. There are three central characters here, played by Maggie Smith, Kevin Kline and Kristin Scott Thomas, with the sum of their ages totaling 203. Most of the action (if you can call it that) takes place inside an old, dusty apartment building in Paris. Most of the conversation is about finances, rent and property law. There you have it — the kind of movie that would have my brothers run screaming from the room in a frantic stampede and take cover in the nearest theater playing "The Avengers."