How to fit Tkinter listbox to contents

Resetting the listbox width worked for me. I used the Oblivion's answer and noticed that the width is always zero.

listbox = tk.Listbox(master, selectmode=tk.SINGLE)
listbox.config(width=0)

I also recommend to reset the root window geometry after reloading a content of the list. Otherwise if user manually extends a window the window would stop accommodate size of its content.

root.winfo_toplevel().wm_geometry("")

just give width and height 0 as below

listbox.config(width=0,height=0)

tkListAutoWidth.py shows one way to do it.

Edit:

So you might have something along the lines of,

import tkinter as tk
from tkinter import font


class NewListbox(tk.Listbox):

    def autowidth(self, maxwidth=100)
        autowidth(self, maxwidth)


def autowidth(list, maxwidth=100):
    f = font.Font(font=list.cget("font"))
    pixels = 0
    for item in list.get(0, "end"):
        pixels = max(pixels, f.measure(item))
    # bump listbox size until all entries fit
    pixels = pixels + 10
    width = int(list.cget("width"))
    for w in range(0, maxwidth+1, 5):
        if list.winfo_reqwidth() >= pixels:
            break
        list.config(width=width+w)


if __name__ == "__main__":

    master = tk.Tk()
    listbox = NewListbox(master, selectmode=tk.SINGLE)

    # ...
    # ...
    keys = serverDict.keys()
    for key in sorted(keys):
        listbox.insert("end", key)

    listbox.pack()

    button = tk.Button(master, text="Execute", command=execute)
    button.pack()

    listbox.autowidth()

    master.mainloop()