Tkinter: How to create popup Window or Messagebox

This example shows how to popup Toplevel window or Messagebox.

Second window uses Toplevel instead of Tk and it doesn't need mainloop.

import tkinter as tk
from tkinter.messagebox import showinfo

# --- functions ---

def popup_window():
    window = tk.Toplevel()

    label = tk.Label(window, text="Hello World!")
    label.pack(fill='x', padx=50, pady=5)

    button_close = tk.Button(window, text="Close", command=window.destroy)
    button_close.pack(fill='x')

def popup_showinfo():
    showinfo("ShowInfo", "Hello World!")

# --- main ---

root = tk.Tk()

button_bonus = tk.Button(root, text="Window", command=popup_window)
button_bonus.pack(fill='x')

button_showinfo = tk.Button(root, text="ShowInfo", command=popup_showinfo)
button_showinfo.pack(fill='x')

button_close = tk.Button(root, text="Close", command=root.destroy)
button_close.pack(fill='x')

root.mainloop()

The same using class. All is hidden in __init__.

If App() would have more methods then probably it would need self.root instead of root.

import tkinter as tk
from tkinter.messagebox import showinfo

# --- classes ---

class App():

    def __init__(self):
        root = tk.Tk()

        button_bonus = tk.Button(root, text="Window", command=self.popup_window)
        button_bonus.pack(fill='x')

        button_showinfo = tk.Button(root, text="ShowInfo", command=self.popup_showinfo)
        button_showinfo.pack(fill='x')

        button_close = tk.Button(root, text="Close", command=root.destroy)
        button_close.pack(fill='x')

        root.mainloop()

    def popup_window(self):
        window = tk.Toplevel()

        label = tk.Label(window, text="Hello World!")
        label.pack(fill='x', padx=50, pady=5)

        button_close = tk.Button(window, text="Close", command=window.destroy)
        button_close.pack(fill='x')

    def popup_showinfo(self):
        showinfo("ShowInfo", "Hello World!")

# --- main ---

App()

The same but App can use root or Toplevel as master.

import tkinter as tk
from tkinter.messagebox import showinfo

# --- classes ---

class App():

    def __init__(self, master):
        self.master = master

        button_bonus = tk.Button(master, text="Window", command=self.popup_window)
        button_bonus.pack(fill='x')

        button_showinfo = tk.Button(master, text="ShowInfo", command=self.popup_showinfo)
        button_showinfo.pack(fill='x')

        button_close = tk.Button(master, text="Close", command=master.destroy)
        button_close.pack(fill='x')

    def popup_window(self):
        window = tk.Toplevel()

        label = tk.Label(window, text="Hello World!")
        label.pack(fill='x', padx=50, pady=5)

        button_close = tk.Button(window, text="Close", command=window.destroy)
        button_close.pack(fill='x')

    def popup_showinfo(self):
        showinfo("ShowInfo", "Hello World!")

# --- main ---

root = tk.Tk()
app = App(root)
root.mainloop()

You can also create separated class with popup window.

It needs self.root instead of root because it is used in run() and popup_window().

If PopupWindow() would have more methods then probably it would need self.window instead of window.

import tkinter as tk
from tkinter.messagebox import showinfo

# --- classes ---

class PopupWindow():

    def __init__(self, master):
        #self.master = master
        window = tk.Toplevel(master)

        label = tk.Label(window, text="Hello World!")
        label.pack(fill='x', padx=50, pady=5)

        button_close = tk.Button(window, text="Close", command=window.destroy)
        button_close.pack(fill='x')


class App():

    def __init__(self):
        self.root = tk.Tk()

        button_bonus = tk.Button(self.root, text="Window", command=self.popup_window)
        button_bonus.pack(fill='x')

        button_showinfo = tk.Button(self.root, text="ShowInfo", command=self.popup_showinfo)
        button_showinfo.pack(fill='x')

        button_close = tk.Button(self.root, text="Close", command=self.root.destroy)
        button_close.pack(fill='x')

    def run(self):
        self.root.mainloop()

    def popup_window(self):
        PopupWindow(self.root)

    def popup_showinfo(self):
        showinfo("ShowInfo", "Hello World!")

# --- main ---

app = App()
app.run()

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