threading_example.py

import tkinter as tk    
import time
from tkinter import ttk
from threading import Thread
import random
from multiprocessing import Queue

def background_work(queue, rand):
    time.sleep(rand.random() * 3)
    msg = rand.random()
    queue.put(msg)
    background_work(queue, rand)

root = tk.Tk()
style = ttk.Style()
style.configure('TFrame', background='black')
style.configure('TLabel', background='black', foreground='white')
content = ttk.Frame(root, padding="20 20 20 20")

content.grid(column=0, row=0)

label = ttk.Label(content, text="      ", font=('Helvetica', 48))
label.grid(column = 0,row = 0)

def check_queue():
    if not queue.empty():
        msg = queue.get(0)
        label.configure(text=msg)
    root.after(1000, check_queue)

queue = Queue()
background_thread = Thread(target=background_work, args=[queue, random.Random()])
background_thread.start()
check_queue()
root.mainloop()