make a button open only one window at a time (enable a button by closing a Toplevel window)

python, tkinter

Solution

Use `NewWin.protocol("WM_DELETE_WINDOW", quit_win)` to assign function `quit_win` to the close button.

import tkinter as tk

root = tk.Tk()
root.title('Main Window')
root.geometry('400x400')

def get_new_win():

    NewWin = tk.Toplevel(root)
    NewWin.title('New Window')
    NewWin.geometry('300x300')
    NewWinButton.config(state='disable')

    def quit_win():
        NewWin.destroy()
        NewWinButton.config(state='normal')

    QuitButton = tk.Button(NewWin, text='Quit', command=quit_win)
    QuitButton.pack()

    NewWin.protocol("WM_DELETE_WINDOW", quit_win) 

NewWinButton = tk.Button(root, text='New Window', command=get_new_win)
NewWinButton.pack()

root.mainloop()

BTW:

The `pack()` method returns `None`, not a button instance:

NewWinButton = tk.Button(...).pack()

use this:

NewWinButton = tk.Button(...)
NewWinButton.pack()

Problem

I want `NewWinButton` to create only one new window at a time, which means if ``` if NewWin.winfo_exists() == 1: NewWinButton.config(state='disabled') else: NewWinButton.config(state='normal') ``` I can make this work if I add a button to the new window (`QuitButton` in this example): ``` import tkinter as tk root = tk.Tk() root.title('Main Window') root.geometry('400x400') def get_new_win(): NewWin = tk.Toplevel(root) NewWin.title('New Window') NewWin.geometry('300x300') NewWinButton.config(state='disable') def quit_win(): NewWin.destroy() NewWinButton.config(state='normal') QuitButton = tk.Button(NewWin,text='Quit', command=quit_win).pack() NewWinButton = tk.Button(root,text='New Window', get_new_win).pack() root.mainloop() ``` This works if and only if I use `QuitButton` to close the new window; however, if I use the close button in the new window, then the NewWinButton will remain 'disabled'. Can anyone tell me how to fix this?

Original source