F/X -- Hired to stage a fake murder for the United States Justice Department, a movie special-effects wizard finds himself fighting for his life in a firestorm of lies, corruption, and violence. An energetic thriller, but very contrived and gimmicky. Directed by Robert Mandel. (Rated R) THE MYSTERY OF PICASSO -- An oddity, and a delightful one. Pablo Picasso stars in this 1955 documentary, creating a series of drawings and paintings as the camera rolls. Since he works on one side of the canvas while cinematographer Claude Renoir films the other side, the pictures seem to blossom of their own miraculous accord. This is a good metaphor for Picasso's fabled spontaneity and power of invention, as well as a novel approach to the art-movie genre, which rarely looks so intensely at the creative process in action. In addition to a feast of color and shape, director Henri-Georges Clouzot gives us a touch of suspense as Picasso races to finish a canvas before the camera runs out of film, and even some laughs as the artist criticizes his own work in a painting that just won't come out right. A hammy but happy Georges Auric score rounds out the show. (Rated PG) STRAIGHT THROUGH THE HEART -- A young woman tries just about everything, including a faked pregnancy, to keep her obsessive relationship with an older man. Directed by Doris D"orrie with more irony than insight. (Not rated) TURTLE DIARY -- He clerks in a bookstore; she writes stories for children; and both are ``turtle freaks'' who can't bear the sight of oceanic creatures cooped up in a zoo's aquarium. Their solution: a great turtle heist, cheerfully aided by the animals' own keeper, who's been mulling over the same idea himself. The story focuses mainly on the planning and execution of this compassionate crime, with subplots about the characters' sex lives. John Irvin directed, from a modest but good-hearted Harold Pinter screenplay. (Rated PG) WINTER FLIGHT -- A bird fancier joins the Royal Air Force, wishes he could ``fit in'' with his loutish companions, and lands in a romantic predicament with a pregnant woman. A gentle drama, with a compassionate conclusion that's unfortunately drowned by soap-opera overkill. Directed by Roy Battersby for the ``First Love'' film series of executive producer David Puttnam. (Not rated). RATINGS: Films with ratings other than G may contain varying degrees of vulgar language, nudity, sex, and violence.