Rinse rice in hot water and simmer in 3 cups of water for 1 hour or until tender. Spoon into an 11x7x2 inch baking dish and set aside. Sprinkle 1/4 tsp salt, paprika, and pepper over chicken and set aside. Coat a large skillet with cooking spray; add margarine or butter and place over medium heat until butter melts. Add chicken and cook 4 minutes on each side or until lightly browned. Arrange chicken in a single layer on top of the rice; top with artichokes; and set aside. Add mushrooms to skillet, and saute over medium heat 5 minutes or until tender. Combine remaining 1/2 tsp salt, flour, and next three ingredients; stir well. Add to skillet; cook 3 minutes or until thickened and bubbly, stirring constantly. Spoon over chicken, cover and bake at 375~ for 55 minutes or until thoroughly heated.