Tkinter: Window flash when attempting to click away

Question

Ive been trying to do this for a while now, but haven't figured out a way to do it.

I have a tkinter script, that creates a popup window when a button is pressed. However I don't want the user to be able to click away from this window to any previous windows created. I have got this working with root.grab_set(), however there is no indication to the user that they must stay on that window.

class popup(object):
    def __init__(self, parent):
        self.root=Toplevel(parent)
        self.root.grab_set() #prevents the user clicking on the parent window
                             #But the window doesnt 'flash' when an attempt to click away is made

For example, when you have a window created by the filedialogue module, if you attempt to click onto another window the filedialogue window stays on top and has a 'flashing' animation to let the user know they cant click away. Is there a way I can reproduce this effect? Going through the source of filedialogue hasn't been fruitful for me, and neither have Google searches.

Answer 1

The simplest way i can think to do this is to use an event and the focus commands, along with the windows bell command:

#!python3

import tkinter as tk

class popup(object):
    def __init__(self, parent):
        self.root=tk.Toplevel(parent)
        self.root.title("Popup")
        self.root.bind("<FocusOut>", self.Alarm)

    def Alarm(self, event):
        self.root.focus_force()
        self.root.bell()

main = tk.Tk()
main.title("Main")
pop = popup(main)
main.mainloop()