private void Initialize()
        {
            // Load config if no cached one.
            if (_config == null)
            {
                LoadTodoConfig();
            }

            // Load data if no cached one.
            if (_data == null)
            {
                LoadTodoDatabase();
            }

            // Set settings
            _config.AdjustConfigIndices();
            _data.SyncTagReferences(ref _config);
            SetCurrentTag(null);
        }