// Remove a word from the database and collections.
        public void DeleteWord(Word wordForDelete)
        {
            // Remove the word from the "all" observable collection.
            AllWords.Remove(wordForDelete);
            NeedableWord.Remove(wordForDelete);
            // Remove the word from the data context.

            // Remove the word from the appropriate category.
            switch (wordForDelete.isKnown())
            {
                case true:
                    KnownWords.Remove(wordForDelete);
                    break;
                case false:
                    UnKnownWords.Remove(wordForDelete);
                    break;
                default:
                    break;
            }
            dictionaryDB.Words.DeleteOnSubmit(wordForDelete);
            // Save changes to the database.
            dictionaryDB.SubmitChanges();
        }