Heat oven to 350°F (or 325°F for dark or nonstick pan).
In large bowl, beat 2 cups flour, 1/2 cup powdered sugar, 1/4 cup of the coconut and the butter with electric mixer on low speed, or mix with spoon, until crumbly. Press in ungreased 13x9-inch pan. Bake 20 to 25 minutes or until light golden brown.
Meanwhile, in large bowl, beat remaining 1/4 cup coconut, eggs, granulated sugar, 1/4 cup flour, the baking powder, lemon peel, lemon juice, lime peel and lime juice with electric mixer on low speed, or mix with spoon. Pour over partially baked crust.
Bake 20 to 25 minutes longer or until light golden brown. Run sharp knife around edges of pan to loosen bars.
Cool completely, about 1 hour. Sprinkle with 2 teaspoons powdered sugar.