For the crust combine the butter, shortening, sugar, eggs, flour, cream of tartar, soda and salt thoroughly and press in 3 (8") or 2 (12") greased pizza pans. Bake at 375 degrees for 10 minutes or slightly browned. Cool. While the crust is baking combine 2 cups fruit juice and the cornstarch until thick. Cool. Combine the icing layer ingredients and spread over the cooled crust. Arrange fruit pieces over icing and spread glaze over top. Refrigerate. This works well to make a day ahead.