private DataGridViewRow GetExpressionViewRow( ExpressionList exp )
        {
            var row = new DataGridViewRow();
            row.CreateCells( ExpressionView );

            row.SetValues(
                exp.Enabled,
                exp.ExternalAnd,
                exp.Inverse,
                exp.InternalAnd,
                exp.ToString()
                );

            return row;
        }
        // Expression のボタン操作
        private void Expression_Add_Click( object sender, EventArgs e )
        {
            int insertrow = GetSelectedRow( ExpressionView );
            if ( insertrow == -1 ) insertrow = ExpressionView.Rows.Count - 1;

            var exp = new ExpressionList();

            _group.Expressions.Expressions.Insert( insertrow + 1, exp );
            ExpressionView.Rows.Insert( insertrow + 1, GetExpressionViewRow( exp ) );

            ExpressionUpdated();
        }