Strictly literal or historical-minded types are advised to loosen their laces before seeing David O. Russell‘s Joy (20th Century Fox, 12.25). Don’t be overly attached to the real story of Joy Mangano, the inventor-marketer of the Miracle Mop and Huggable Hangers. It is about Ms. Mangano, of course, but the facts about her struggle and the success of he Ingenious Designs have been treated as starting elements. The movie is about a lot more than just her history…a lot more. Call it a launch pad, a point of embarkation.