CODE EXAMPLE FOR PYTHON

tkintre sub windows

import tkinter as tk
from tkinter import * 

my_w = tk.Tk()
my_w.geometry("200x200")  # Size of the window 
my_w.title("www.plus2net.com")  # Adding a title

# create one lebel 
my_str = tk.StringVar()
l1 = tk.Label(my_w,  textvariable=my_str )
l1.grid(row=1,column=2) 
my_str.set("Hi I am main window")

# child window 
my_w_child=Toplevel(my_w) # Child window 
my_w_child.geometry("200x200")  # Size of the window 
my_w_child.title("www.plus2net.com")

my_str1 = tk.StringVar()
l1 = tk.Label(my_w_child,  textvariable=my_str1 )
l1.grid(row=1,column=2) 
my_str1.set("Hi I am Child window")

my_w.mainloop()