Specify parent of a tkinter widget with a context manager

set_parent.py

"""Specify parent of a tkinter widget
with a context manager"""
import tkinter as tk
from contextlib import contextmanager


@contextmanager
def set_parent(new_parent):
    old_root = tk._default_root
    tk._default_root = new_parent
    try:
        yield new_parent
    finally:
        tk._default_root = old_root


def on_button_press():
    with set_parent(tk.Toplevel()) as child:
        tk.Label(text="In the child window").pack()
        child.wait_window()
    
    tk.Label(text="In the main window again").pack()


root = tk.Tk()

tk.Label(text="In the main window").pack()
tk.Button(text="Press me", command=on_button_press).pack()

root.mainloop()