How to Handle Window Close Events in Tkinter?

Handling Window Close Events in Tkinter

In Tkinter, when a user clicks the "X" button on a window, the WM_DELETE_WINDOW protocol is triggered. To handle this event, you can register a protocol handler.

Protocol Handlers

Protocol handlers allow you to define a specific action to be taken when a protocol is triggered. For WM_DELETE_WINDOW, this action typically involves closing the window or prompting the user for confirmation.

Installing a Protocol Handler

To install a protocol handler, use the protocol method on a Tk or Toplevel widget. The syntax is:

<code class="python">widget.protocol("protocol_name", handler)</code>

where:

• protocol_name is the name of the protocol (e.g., "WM_DELETE_WINDOW")
• handler is the function to be called when the protocol is triggered

Example Usage

The following example demonstrates how to handle the window close event in Tkinter:

<code class="python">import tkinter as tk
from tkinter import messagebox

root = tk.Tk()

def on_closing():
    if messagebox.askokcancel("Quit", "Do you want to quit?"):
        root.destroy()

root.protocol("WM_DELETE_WINDOW", on_closing)
root.mainloop()</code>

In this example:

• The on_closing function is defined to prompt the user for confirmation before closing the window.
• The protocol method is used to register on_closing as the handler for the WM_DELETE_WINDOW protocol.
• The mainloop method runs the main event loop, waiting for events like window close requests.

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