dmenu: how to create submenu

Question

In a simple way, how to create a submenu of dmenu, manpage doesn't help much also archlinux, gentoo wikipage,

Use case: I'd to pip a list of note files to dmenu and then list all that files under a submenu of dmenu.

Steps:

open dmenu
type: notes
submenu with list of notes (piped list files under a folder)

Answer 1

Here's a proof of concept:

#!/bin/bash
#
# Dmenu picker with sub entries

options=("Note books" Files)
choice=$(printf "%s\n" "${options[@]}" | dmenu)
[ $? = 0 ] || exit

case $choice in
    "Note books")
        cd ~/notebooks
        note=$(ls | dmenu)
        [ $? = 0 ] || exit
        gedit "$note"
        ;;
    Files)
        cd ~
        file=$(ls | dmenu)
        [ $? = 0 ] || exit
        xdg-open "$file"
        ;;
esac

If you make that script executable in your $PATH, then dmenu_run can find it also.