# tk_super_listbox_multiselect.py

# tk_super_listbox_multiselect.py

import tkinter as tk
from collections import deque

def do_toggle(i):
    if i in toggle:
        listbox.select_clear(i)
        toggle.remove(i)
    else:
        listbox.select_set(i)
        toggle.append(i)

def on_drag(event):
    global prev_2_lines
    i = listbox.nearest(event.y)
    if i != prev_2_lines[1]:
        if i in prev_2_lines:
            do_toggle(prev_2_lines[1])
        do_toggle(i)
        prev_2_lines.append(i)

root = tk.Tk()

items = [f"Item {i+1}" for i in range(30)]

toggle = []
prev_2_lines = deque(maxlen=2)
prev_2_lines.extend([-1, -1])

listbox = tk.Listbox(root, selectmode=tk.MULTIPLE)
listbox.bind("<B1-Motion>", on_drag)

for item in items:
    listbox.insert(tk.END, item)

scrollbar = tk.Scrollbar(root, orient="vertical", command=listbox.yview)
listbox.configure(yscrollcommand=scrollbar.set)

listbox.pack(side=tk.LEFT, fill=tk.BOTH, expand=True)
scrollbar.pack(side=tk.RIGHT, fill=tk.Y)

root.mainloop()