Why do I have to double click to change the relief of my button object ? (tkinter)

Question

Good afternoon!

Why do I have to double click to change the relief of my button object ?

In my method bind, my first parameter is Button-1, I don't understand...

Here is my code, thank you in advance.

from tkinter import *

def sunken(event):
    button = event.widget # détecte le bouton sur lequel on clique
    button['relief'] = 'sunken' # changement de relief

root = Tk()

for i in range(8):
    for j in range(8):
        myButton = Button(root, text='', relief='raised')
        myButton.grid(row=i, column=j)
        myButton.bind("<Button-1>", sunken)

root.mainloop()

Python 3.x

I apologize for my english, I'm french...

Answer 1

The response of my question

from tkinter import *

def sunken(event):
    button = event.widget # detecte le bouton sur lequel on clique
    button['relief'] = 'sunken' # changement de relief

root = Tk()

for i in range(8):
    for j in range(8):
        myButton = Button(root, text='', state='disabled')
        myButton.grid(row=i, column=j)
        myButton.bind("<Button-1>", sunken)

root.mainloop()