Combine the vinegar, water, seasonings and onion and use to marinate the rabbit pieces in a covered crock in the refrigerator for a day or two. Remove and drain the rabbit pieces. Coat them with flour and brown well in 1/4 inch hot butter in a heavy skillet. Remove excess fat and add marinating liquid. Cover and simmer for 1 hour or until tender. Remove the rabbit meat to a hot platter and thicken the gravy with flour or with finely crushed ginger snaps.