in a large sauce pan, combine the sugar, cornstarch and salt. slowly add water, stirring until smooth. stir in 2 cups blueberries. bring to a boil; cook and stir 2 min or until thickened. remove from the heat; cool to room temperature.
spoon the other two cups blueberries into the crust;top with room temperature mixture. cover an refrigerate 2 hours. ummmmmm