White Texas Sheet Cake

1/2 cup shortening
2 cups granulated sugar
2 egg whites
1 teaspoon salt
1 teaspoon baking soda
2 cups all-purpose flour
1 3/4 cups buttermilk
1 teaspoon vanilla extract
1 teaspoon almond extract
1/2 cup (1 stick) margarine, melted
1/3 cup buttermilk
1/2 cup coconut
1 pound confectioners