In a saucepan, bring the water to a boil with the rice. Cover and simmer over moderately low heat until tender, 45 minutes.
In a medium skillet, cook the onion and garlic in the butter over moderate heat until softened. Stir in the rice, season with salt and pepper, cover and keep warm.
In a large skillet, heat 1 tablespoon of the oil. Add the shrimp and 1/2 teaspoon of the rosemary; season with salt and pepper. Cook over moderate heat, turning once, until just white throughout; transfer to a plate.
Add 1 tablespoon of the oil to the skillet; increase the heat to moderately high. Add half of the squid and 1/4 teaspoon of the rosemary; season with salt and pepper. Cook, turning once, until the squid is just firm, 1 minute; transfer to the plate. Repeat with the remaining squid, 1/2 tablespoon of oil and 1/4 teaspoon of rosemary.
Add the wine to the skillet and cook for 1 minute, scraping up any browned bits from the bottom. Stir in the tomato sauce and the seafood; cook just until heated through. Season with salt and pepper. Mound the rice on plates, top with the seafood and sauce and serve right away.
