Melt butter or margarine, blend in the flour, and add the salt. Slowly pour in the milk and stir until the mixture thickens. The sauce should cook for about 5 minutes after it reaches the boiling point, with constant stirring. In a separate kettle, boil the corn in the water with the onions, pepper and paprika for 15 minutes. Add the white sauce and cook together for 10 minutes. Sprinkle a little parsley over each serving.