python - I'm trying to print something letter by letter in a new window with tkinter import, but when I run it through the terminal the window doesn't pop up -

from tkinter import *  import time  while true:      message in "hello world":         time.sleep(.5)  root = tk()  lb = listbox(root, height=3)  lb.pack()  lb.insert(end, message)  lb.insert(end,"second entry")  lb.insert(end,"third entry")  root.mainloop() 

you have use root.after call function add single letter, , use root.after call same function add next letter.

from tkinter import *  # --- functions ---  def add_letter(text):     if text: # if text not empty         # add first letter text         lb.insert(end, text[0])         # call again without first letter         root.after(500, add_letter, text[1:])  # --- main ---  root = tk() lb = listbox(root, height=15) lb.pack()  # first call after 500ms  root.after(500, add_letter, "hello world")  root.mainloop() 

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edit: moving text :) using text , reversed text

from tkinter import *  # --- functions ---  def add_letter(text):     if text: # if text not empty         # add first letter text         lb.insert('1.0', text[0]) # put @ beginning of line         # call again without first letter         root.after(250, add_letter, text[1:])  # --- main ---  root = tk() lb = text(root) lb.pack()  text = ''.join(reversed("hello world of python , tkinter")) # first call after 250ms  root.after(250, add_letter, text)  root.mainloop()