Mosaic Dessert Bars

I was expecting some guests this week-end. Since the weather is turning warm, I thought of serving something "cool" as the dessert. This recipe met my criteria of a cold dessert that is so attractive and eye-catching: "cool" indeed.
Recipe source: Kraft
Ingredients:
5-1/2cups boiling water, divided
1pkg. (3 oz.) JELL-O Strawberry Flavor Gelatin
1pkg. (3 oz.) JELL-O Lime Flavor Gelatin
1pkg. (3 oz.) JELL-O Orange Flavor Gelatin
1pkg. (3 oz.) JELL-O BlueberryFlavor Gelatin
2env. KNOX Unflavored Gelatine
1/2cup cold water
1can (14 oz.) sweetened condensed milk
Method:
Add 1 cup boiling water to each flavor fruit gelatin mix in separate bowls. Stir at least 2 min. until completely dissolved. Pour each flavor of gelatin into separate small shallow food storage container sprayed with cooking spray. Refrigerate 2 hours or until firm.
Sprinkle unflavored gelatine over cold water; let stand 1 min. Stir in 1-1/2 cups boiling water. Add condensed milk; mix well. Cool slightly.
Cut flavored gelatin into cubes. Randomly place cubes in 13x9-inch pan sprayed with cooking spray. Pour milk mixture over cubes; stir very gently if necessary to evenly distribute gelatin cubes. Refrigerate 2 hours or until firm before cutting into bars.