Tkinter - Update All Widgets

Question

Hello I am trying to change background by button on tkinter. I have a button that changes background of mainWindow but when button pressed it doesn't change immediately. I think tk.update() command is useless because I made too much test with it and nothing happened.

Here's my code:

import tkinter as tk

def ChangeBg():
    global bgColor
    bgColor = 'white'
    mainWindow.update()

bgColor = 'black'

root = tk.Tk()
mainWindow = tkToplevel()
mainWindow.geometry('500x500')

mainWindow.config(bg=bgColor)

btn = tk.Button(mainWindow, text='change background', command=ChangeBg)
btn.pack()

tk.mainloop()

I guess you will say "Why don't you just use mainWindow.config(bg=bgColor) ?". Because in my main code I have to store color in variables and there will be a lot more widgets. Like generalBtnColor, generalForeground, generalTextColor . I can write a lot of codes for update all widgets itself but this is Python and I believe there is a short way.

Answer 1

I added mainWindow.config(bg='white') . Also changed in line 11 and 14.

import tkinter as tk


def ChangeBg():
    global bgColor
    mainWindow.config(bg='white')
    mainWindow.update()
    


root = tk.Tk()
mainWindow = tk.Toplevel()
mainWindow.geometry('500x500')

mainWindow.config(bg = 'black')

btn = tk.Button(mainWindow, text='change background', command=ChangeBg)
btn.pack()

tk.mainloop()

Output: Current black:

After changing to white: