move one step down when marking

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example code

        # Mark files for operation.
        ${FFF_KEY_YANK:=y}|\
        ${FFF_KEY_MOVE:=m}|\
        ${FFF_KEY_TRASH:=d}|\
        ${FFF_KEY_LINK:=s}|\
        ${FFF_KEY_BULK_RENAME:=b})
            mark "$scroll" "$1"
            ((scroll < list_total)) && {
                ((scroll++))
                ((y < max_items)) && ((y++))

                print_line "$((scroll-1))"
                printf '\n'
                print_line "$scroll"
                status_line
            }
        ;;