Combine cranberries, two cups sugar and water; heat to boiling point, stirring until sugar is dissolved. Continue to boil rapidly until berries pop open, five to ten minutes. Drain and measure cranberries to make one cup; reserve.
Sift together flour, baking powder, salt and soda. Cream shortening and 2/3 cup sugar. Add eggs, one at a time, beating well after each addition. Blend in nuts and bananas alternately with dry ingredients. Fold in reserved cup of drained, cooked cranberries.
Bake in greased loaf pan in oven preheated to 350 degrees for one hour or until wooden pick inserted in center comes out clean. If desired, brush top with glaze and decorate with chopped walnuts. Glaze: Combine 1/4 cup water and 1/4 cup sugar; boil until slightly syrupy, about two minutes.