Why do I get an extra empty window in Tkinter?

Question

Here is my code:

from tkinter import *

OPTIONS = ["Available","Busy","Invisible","Away"]

now = Toplevel()
variable = StringVar(now)
variable.set(OPTIONS[0]) # default value
details = {"U_status":""}
def verify():
    global u_status
    details["U_status"]=variable.get()
    print ("value is:" + variable.get())
    now.destroy()
def status():
    w = OptionMenu(now, variable, *OPTIONS)
    w.pack()
    button = Button(now, text="OK", command=verify, relief='flat')
    button.pack()
if __name__=='__main__':
    status()
    mainloop()

While running the above code, along with the window (I wanted) another empty window appears. Can anyone figure out what is wrong in this code?

Delrius Euphoria · Accepted Answer · 2020-11-12T06:34:48.190

2

Here now = Toplevel() should be replaced with Tk(), like:

now = Tk()

When you use Toplevel() a Tk() window is made in the background, if its not already made(your case), and that is the reason you are getting a blank new window. Actually that blank window is your main window.

Toplevel() is used to make child windows for the parent Tk() windows,ie, if you want sub windows within your main window(now), you will use Toplevel(). Because more than one Tk() in your code will cause some errors later on.

edited Nov 12 '20 at 06:34

answered Nov 12 '20 at 06:30

Delrius Euphoria

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But, once I do this I will be facing errors in deleting a window using .destroy() – Code Carbonate Nov 12 '20 at 06:34
@CodeCarbonate `now.destroy()` will destroy the main window, in your case, just press the button and it should destroy the window. – Delrius Euphoria Nov 12 '20 at 06:35
Suppose I name a variable called now and set it the value of Tk(), if I want to delete only the main window and to keep other parts of the program running I use now.destroy(). But I get an error. – Code Carbonate Nov 12 '20 at 06:38
What other part of program do you mean? Destroying a `Tk()` will destroy the whole app. – Delrius Euphoria Nov 12 '20 at 06:40
Just like resetting the value of now to Tk() and displaying the same window with a different content after destroying now. – Code Carbonate Nov 12 '20 at 06:47
I would say to make a new window with `Toplevel()` and show the new contents there – Delrius Euphoria Nov 12 '20 at 06:52

Reblochon Masque · Answer 2 · 2020-11-12T11:51:22.100

The blank window is actually the root window of your app that tkinter creates by default. You probably want to be explicit, and create a tk.Tk() root, and keep a reference to it.

New windows can be spawned and destroyed at leisure; your app will continue to exist as long as you keep the root active.

Maybe something like this:

import tkinter as tk


def verify():
    now = tk.Toplevel(root)
    details["U_status"] = variable.get()
    txt = f'value is: {details["U_status"]}'
    tk.Label(now, text=txt).pack()
    now.after(3000, now.destroy)
    
def status():
    tk.OptionMenu(root, variable, *OPTIONS).pack()
    tk.Button(root, text="OK", command=verify, relief='flat').pack()
    
    
if __name__=='__main__':
    
    OPTIONS = ["Available", "Busy", "Invisible", "Away"]
    
    root = tk.Tk()
    variable = tk.StringVar(root)
    variable.set(OPTIONS[0])
    details = {"U_status": ""}
    status()
    root.mainloop()

But, when I run the code you gave, an error arises stating NameError: name 'mainloop' is not defined — Code Carbonate, Nov 12 '20 at 11:32
Yes, it has to be `root.mainloop()`, sorry, my bad - I corrected it. — Reblochon Masque, Nov 12 '20 at 11:51

Why do I get an extra empty window in Tkinter?

2 Answers2