In medium bowl, combine flour and confectioners' sugar, cut in margarine until crumbly. Press onto bottom of lightly greased 13 x 9" baking pan; bake @ 350 degrees for 15 minutes. In large bowl, mix eggs, granulated sugar, baking powder and lemon juice. Pour over crust; top with coconut. Bake 20 minutes or until golden. Cool. Cut into bars. Store in refrigerator.