In a large shallow dish, combine the flour, salt and pepper. Add chicken, a few pieces at a time, and turn to coat. , In a large skillet, melt butter; cook chicken until juices to clear. Add onion and celery; cook for 3 minutes. Stir in potatoes and carrots. , In a small bowl, combine the broth, thyme, ketchup and cornstarch; stir into skillet. Bring to a boil. Reduce heat; cover and simmer for 15-20 minutes or until the vegetables are tender.