5 Best Ways to Close Only the Top-Level Window in Python Tkinter

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πŸ’‘ Problem Formulation: When working with Python’s Tkinter library, you might encounter a situation where you have multiple windows open, and you want to close just the top-level one without terminating the entire application. This is especially common in GUI applications where multiple dialogs or child windows are involved. How do you close only the top-level window without affecting other windows? Let’s go over some methods to achieve this.

Method 1: Using the destroy() Method

One standard way to close the top-level window in Tkinter is by invoking the destroy() method on the top-level window object. This method effectively closes the window and terminates its mainloop, without closing the entire application if there are other windows open.

Here’s an example:

import tkinter as tk

root = tk.Tk()
top = tk.Toplevel(root)
top.title("Top-Level Window")

def close_top():
    top.destroy()

close_button = tk.Button(top, text="Close", command=close_top)
close_button.pack()

root.mainloop()

The output of this code snippet is the closing of only the top-level window when the “Close” button is clicked, while the root window remains open.

This code snippet creates a root window and a top-level window, each with their respective widgets. When the user presses the “Close” button on the top-level window, the close_top() function is called, triggering the destroy() method and closing just the top-level window without terminating the entire program.

Method 2: Overriding the Window Close Button

To prevent the default behavior of closing the entire application when the window close button is clicked, you can override the close button’s functionality to only destroy the top-level window. This keeps the root window or any other windows open.

Here’s an example:

import tkinter as tk

root = tk.Tk()
top = tk.Toplevel(root)

top.protocol("WM_DELETE_WINDOW", top.destroy)

root.mainloop()

The output of this code is that clicking the close button (typically an “X” at the corner of the window) on the top-level window will close only that window.

With the protocol() method, we are changing the behavior of the “WM_DELETE_WINDOW” event (which is triggered when the window’s close button is clicked), to execute the destroy() method for the top-level window only. This ensures that other windows remain unaffected when the top-level window is closed.

Method 3: Using the withdraw() Method

The withdraw() method is another Tkinter function that can be used to hide a window without terminating its process. It can be particularly useful when you want to close the top-level window but may want to reopen it again without losing its state.

Here’s an example:

import tkinter as tk

root = tk.Tk()
top = tk.Toplevel(root)

def hide_top():
    top.withdraw()

hide_button = tk.Button(top, text="Hide", command=hide_top)
hide_button.pack()

root.mainloop()

This code will result in the top-level window being hidden from view when the “Hide” button is clicked, without closing the root window.

The hide_top() function is connected to a button within the top-level window. When this button is clicked, the withdraw() method is called on the top-level window, which effectively hides it. Unlike destroy(), this window can be later shown again using deiconify().

Method 4: Disconnecting the Top-Level Window from the Mainloop

Creating the top-level window without tying it to the root window’s mainloop can allow for it to be closed independently. Although this approach is unconventional, it might be useful in certain scenarios.

Here’s an example:

import tkinter as tk

def create_toplevel():
    top = tk.Toplevel()
    top.title("Independent Top-Level")
    top.mainloop()

root = tk.Tk()
open_button = tk.Button(root, text="Open Independent Top-Level", command=create_toplevel)
open_button.pack()

root.mainloop()

With this code, closing the top-level window created by pressing the “Open Independent Top-Level” button will only affect that window and not the main application.

By running a separate mainloop() for the top-level window, you are splitting it off from the main application loop. This makes the top-level window behave as an independent entity, but be aware that it could lead to unexpected behavior and is not recommended without a good understanding of Tkinter’s event loop.

Bonus One-Liner Method 5: Using Lambda Functions

A quick and easy one-liner that allows you to close the top-level window involves using a lambda function inline with the button’s command parameter.

Here’s an example:

import tkinter as tk

root = tk.Tk()
top = tk.Toplevel(root)

close_button = tk.Button(top, text="Close", command=lambda: top.destroy())
close_button.pack()

root.mainloop()

This code snippet will provide the same outcome as the first method with a more concise syntax.

Using a lambda function, we immediately pass the destroy() method of the top-level window as a command parameter to the button. This simplifies the code by negating the need for an explicitly defined function.

Summary/Discussion

  • Method 1: Using the destroy() Method. This method is straightforward and ideal for most scenarios, and it’s the recommended way to close a window in Tkinter. However, it completely removes the window, so you cannot bring it back without re-creating it.
  • Method 2: Overriding the Window Close Button. It provides a seamless user experience by intercepting the default close action, which is familiar to users. Its limitation is that you have to set it up for each top-level window you create.
  • Method 3: Using the withdraw() Method. Offers the ability to hide and reuse a window, preserving its state. While flexible, users may not realize that the window is still running in the background, potentially leaving unnoticed processes open.
  • Method 4: Disconnecting the Top-Level Window from the Mainloop. Useful for creating a truly independent window, but it’s not typical and can complicate the program’s flow and event management.
  • Method 5: Using Lambda Functions. A quick and compact way to close the window, but may not be as clear to read as a separately defined function, especially for beginners.