CODEWITHSUNDEEP
pythonuser-interfacetkinter
Nathanael Skrepek
Nathanael Skrepek

Reputation: 169

window freezes in Python 3

I am using python3 on a mac and run scripts with the IDLE which comes automatically with the python3 installation.

I am trying to make an alert to the user and found the command tkinter.messagebox.showinfo("title","some text")

So I i tried a minimal script to check if I can get along with that command

import tkinter 

tkinter.messagebox.showinfo("test" , "blabla")

The window is displayed correctly but it doesn't respond when I click on the "OK" button. Addtionally there is a second empty window which appears when I start the script.

What is the explanation for this or at least how can I fix that?

Upvotes: 0

Views: 965

Answers (1)

Bryan Oakley
Bryan Oakley

Reputation: 385800

tkinter isn't designed to work this way. Every tkinter requires a root window. If you don't explicitly create one (and you didn't), one will be created for you. That's what the blank window is.

Also, a tkinter GUI can't function properly unless it has a running event loop. This is necessary because some functions, such as responding to buttons and redrawing the window, only happens in response to events. If the event loop isn't running, events can't be processed.

Bottom line: the dialogs aren't designed to be used outside of the context of a proper tkinter app.

Wrapper for standalone use

The following code can be used to display one of the dialogs in standalone mode. It works by creating and hiding a root window, displaying the dialog, and then destroying the root window.

import tkinter as tk
from tkinter import messagebox

def show_dialog(func, *args, **kwargs):
    # create root window, then hide it
    root = tk.Tk()
    root.withdraw()

    # create a mutable variable for storing the result
    result = []

    # local function to call the dialog after the
    # event loop starts
    def show_dialog():

        # show the dialog; this will block until the
        # dialog is dismissed by the user
        result.append(func(*args, **kwargs))

        # destroy the root window when the dialog is dismissed
        # note: this will cause the event loop (mainloop) to end
        root.destroy()

    # run the function after the event loop is initialized
    root.after_idle(show_dialog)

    # start the event loop, then kill the tcl interpreter
    # once the root window has been destroyed
    root.mainloop()
    root.quit()

    # pop the result and return
    return result.pop()

To use it, pass the dialog you want as the first option, followed by dialog-specific options.

For example:

result = show_dialog(messagebox.askokcancel, "title", "Are you sure?")
if result:
    print("you answered OK")
else:
    print("you cancelled")

Upvotes: 2

Related Questions