Spoon the mangoes, blueberries with the syrup, pineapple pieces with the syrup, sugar and water into a saucepan and cook over medium heat until the mixture is syrupy, for about 30 minutes. Stir in the coconut, vanilla and half of the walnuts and set aside. Preheat the oven to 200°C and lightly spray a 23cm x 32cm baking tray with a non-stick spray.
Put one layer of the phyllo on a working surface and lightly brush with the melted butter. Top with the next two buttered phyllo sheets.
Spread half of the fruit mixture in the centre of the three-layered pastry sheets and fold the shorter sides over the filling, then fold over the long edges to form a roll. Carefully transfer to the prepared baking tray with the join on the bottom.
Using a sharp knife, score the top of the pastry into portions and brush lightly with butter.
Repeat this procedure with the remaining ingredients. Bake until golden for about 30 – 40 minutes. Sprinkle with the extra coconut and walnuts and serve with custard while still hot.