Disable window controls when a messagebox is created in tkinter

Question

Is there any way to disable all windows when a messagebox popup is created in tkinter?

Here's the code:

from tkinter import *
from tkinter import messagebox

def show():
    messagebox.showinfo("Test Popup", "Hello world")

root = Tk()
root.title("Main Window")
root.geometry("500x500")

toplevel = Toplevel(root)
toplevel.title("Toplevel Window")
toplevel.geometry("300x300")

show_button = Button(root , text = "Show popup" , command = show)
show_button.place(x = 200 , y = 200)

mainloop()

Here when the messagebox pops up, I don't want the user to be able to interact with any other Tk or Toplevel windows until that popup is destroyed.

(I tried using the parent attribute of the messagebox, but it only disables one window.)

Is there any way to achieve this in tkinter?

It would be great if anyone could help me out.

Answer 1

I don't think it is possible to prevent all interactions with the windows like moving them around (except if you use .overrideredirect(True) which will make the window decoration disappear and the widow will stop being handled by the window manager).

However, it is possible to

1. prevent the toplevel to come on top of the popup

2. disable the "close" button of both the root window and toplevel when the popup is displayed

For both I use the following general idea in show():

def show():
    # modify state of root and toplevel to make them less interactive
    # ...
    messagebox.showinfo("Test Popup", "Hello world", parent=root)
    # put root and toplevel back in their normal state
    # ...

For 1. I use root.attributes('-topmost', True) before displaying the popup, which inherits this property from root and therefore will stay on top of toplevel.

For 2. I use window.protocol("WM_DELETE_WINDOW", lambda: quit(window)) which calls quit(window) when the user clicks on the close button of window. In quit(), I check whether the popup is opened before destroying the window:

def quit(window):
    if not popup:
        window.destroy()

popup is a global variable which value is changed in show().

Full code:

import tkinter as tk
from tkinter import messagebox

def quit(window):
    if not popup:  # destroy the window only if popup is not displayed
        window.destroy()

def show():
    global popup
    popup = True
    root.attributes('-topmost', True)
    messagebox.showinfo("Test Popup", "Hello world", parent=root)
    root.attributes('-topmost', False)
    popup = False

root = tk.Tk()
popup = False
root.protocol("WM_DELETE_WINDOW", lambda: quit(root))
root.title("Main Window")
root.geometry("500x500")

toplevel = tk.Toplevel(root)
toplevel.protocol("WM_DELETE_WINDOW", lambda: quit(toplevel))
toplevel.title("Toplevel Window")

show_button = tk.Button(root, text="Show popup", command=show)
show_button.pack()

root.mainloop()

You can probably add some more stuff in show(), e.g. .resizable(False, False) if you don't want the user to be able to resize the windows when the popup is displayed.

Answer 2

After experimenting for a few days, I finally found the solution.

The basic idea here is to get all the child widgets of a window, check whether the child is an instance of Tk or Toplevel, and apply the -disabled attribute to them.

Here's the implementation:

from tkinter import *
from tkinter import messagebox

def disable_windows(window):
    for child in window.winfo_children(): # Get all the child widgets of the window
        if isinstance(child, Tk) or isinstance(child, Toplevel): # Check if the child is a Tk or Toplevel window so that we can disable them
            child.attributes('-disabled', True)
            disable_windows(child)

def enable_windows(window):
    for child in window.winfo_children(): # Get all the child widgets of the window
        if isinstance(child , Tk) or isinstance(child , Toplevel): # Check if the child is a Tk or Toplevel window so that we can enable them
            child.attributes('-disabled' , False)
            enable_windows(child)

def increase_popup_count():
    global popup_count
    popup_count += 1
    if popup_count > 0: # Check if a popup is currently active so that we can disable the windows
        disable_windows(root)
    else: # Enable the windows if there is no active popup
        enable_windows(root)

def decrease_popup_count():
    global popup_count
    popup_count -= 1
    if popup_count > 0: # Check if a popup is currently active so that we can disable the windows
        disable_windows(root)
    else: # Enable the windows if there is no active popup
        enable_windows(root)

def showinfo(title, message): # A custom showinfo funtion
    increase_popup_count() # Increase the 'popup_count' when the messagebox shows up
    messagebox.showinfo(title , message)
    decrease_popup_count() # Decrease the 'popup_count' after the messagebox is destroyed

def show():
    showinfo("Test Popup", "Hello world")

root = Tk()
root.title("Main Window")
root.geometry("500x500")

popup_count = 0

toplevel = Toplevel(root)
toplevel.title("Toplevel Window")
toplevel.geometry("400x400")

toplevel_2 = Toplevel(toplevel)
toplevel_2.title("Toplevel Window of Another Toplevel")
toplevel_2.geometry("300x300")

show_button = Button(root , text = "Show popup" , command = show)
show_button.place(x = 200 , y = 200)

mainloop()