public override void Start()
        {
            base.Start();

            _toolContext = new StudyFilterToolContext(this);
            _toolset     = new ToolSet(new StudyFilterToolExtensionPoint(), _toolContext);
            _actions     = _toolset.Actions;

            // restore columns from settings
            _columns.Deserialize(_settings.Columns);
        }
        public override void Stop()
        {
            // save columns to settings
            _settings.Columns = _columns.Serialize();

            _actions = null;
            _toolset.Dispose();
            _toolset     = null;
            _toolContext = null;

            _table.Filter();

            base.Stop();
        }
        public override void Stop()
        {
            // save columns to settings
            _settings.Columns = _columns.Serialize();

            _actions = null;
            _toolset.Dispose();
            _toolset     = null;
            _toolContext = null;

            _table.Filter();

            base.Stop();

            // dispose any remaining study items now
            if (_masterList.Count > 0)
            {
                foreach (var item in _masterList)
                {
                    item.Dispose();
                }
                _masterList.Clear();
            }
        }