rem: return_value = gsb_transaction_data_get_marked_transaction ( gsb_transaction_data_get_transaction_number (transaction_1 ))- gsb_transaction_data_get_marked_transaction ( gsb_transaction_data_get_transaction_number (transaction_2 ));
add: return_value = gsb_transaction_data_get_marked_transaction ( transaction_number_1)- gsb_transaction_data_get_marked_transaction ( transaction_number_2);
context: gint gsb_transactions_list_sort_by_mark ( GtkTreeModel *model,					  GtkTreeIter *iter_1,					  GtkTreeIter *iter_2,					  GtkSortType sort_type ){    gint return_value;    /*     general test first (white line, other rows of the transaction */    return_value = gsb_transactions_list_general_test ( model,							iter_1,							iter_2,							sort_type );    if ( return_value )	return return_value;    return_value = gsb_transactions_list_breakdown_test ( sort_type );    if ( return_value )	return return_value;    return_value = gsb_transaction_data_get_marked_transaction ( gsb_transaction_data_get_transaction_number (transaction_1 ))- gsb_transaction_data_get_marked_transaction ( gsb_transaction_data_get_transaction_number (transaction_2 ));    if ( return_value )	return return_value;    else	return gsb_transactions_list_sort_by_transaction_date_and_no();}