Preheat oven to 350 degrees. In a mixing bowl, beat together 1.5 cups flour, half cup butter and one third cup brown sugar. Press into the bottom of an ungreased 13x9x2 inch baking pan. Bake for 10 minutes.
In another bowl, beat the eggs. Stir in the coconut, 0.75 cup brown sugar, 2 tablespoons flour, baking powder, vanilla extract and salt. Stir in the chopped nuts. Spread over the baked mixture. Bake for 20 minutes longer, or until set.
Meanwhile, combine the powdered sugar and melted butter. Add enough lemon juice to make a glaze. Drizzle over the warm bars in the pan. Cut into squares.