Custom WP_List_Table: How to create an unapproved row?

Well, the yellow comes from

<tr class="unapproved">

and this is, in crass contrast to what the usual WP_List_Table introduction might suggest, not an automatism, but generated very verbatim:

See e.g. single_row() in wp-admin/includes/class-wp-comments-list-table.php:

function single_row( $a_comment ) {
                global $post, $comment;

                $comment = $a_comment;
                $the_comment_class = join( ' ', get_comment_class( wp_get_comment_status( $comment->comment_ID ) ) );

                $post = get_post( $comment->comment_post_ID );

                $this->user_can = current_user_can( 'edit_comment', $comment->comment_ID );

                echo "<tr id='comment-$comment->comment_ID' class="$the_comment_class">";
                echo $this->single_row_columns( $comment );
                echo "</tr>\n";
        }

which overrides the standard method inherited from wp-admin/includes/class-wp-list-table.php