Tkinter example code for multiple windows, why won't buttons load correctly?

Question

I am writing a program which should:

1. Open a window with the press of a button.
2. Close the newly opened window with the press of another button.

I'm using classes so I can insert the code into a larger program later. However, I can't get my buttons to load correctly.

import tkinter as tk

class Demo1(tk.Frame):
    def __init__(self):
        tk.Frame.__init__(self)
        self.pack()
        self.master.title("Demo 1")
        self.button1 = tk.Button(self, text = "Button 1", width = 25,
                               command = self.new_window)
        self.button1.grid(row = 0, column = 1, columnspan = 2, sticky = tk.W+tk.E+tk.N+tk.S)

    def new_window(self):
        self.newWindow = Demo2()

class Demo2(tk.Frame):
    def __init__(self):
        new = tk.Frame.__init__(self)
        new = tk.Toplevel(self)
        new.title("Demo 2")
        new.button = tk.Button(text = "Button 2", width = 25,
                               command = self.close_window)
        new.button.pack()

    def close_window(self):
        self.destroy()

def main():
    Demo1().mainloop()

if __name__ == '__main__':
    main()

Eudoxia

Answer 1

I rewrote your code in a more organized, better-practiced way:

import tkinter as tk

class Demo1:
    def __init__(self, master):
        self.master = master
        self.frame = tk.Frame(self.master)
        self.button1 = tk.Button(self.frame, text = 'New Window', width = 25, command = self.new_window)
        self.button1.pack()
        self.frame.pack()

    def new_window(self):
        self.newWindow = tk.Toplevel(self.master)
        self.app = Demo2(self.newWindow)

class Demo2:
    def __init__(self, master):
        self.master = master
        self.frame = tk.Frame(self.master)
        self.quitButton = tk.Button(self.frame, text = 'Quit', width = 25, command = self.close_windows)
        self.quitButton.pack()
        self.frame.pack()

    def close_windows(self):
        self.master.destroy()

def main(): 
    root = tk.Tk()
    app = Demo1(root)
    root.mainloop()

if __name__ == '__main__':
    main()

Result:

Ky

@Eudoxia It depends. Generally, running two mainloop()s on two Tk() windows is looked down upon. However, if you want multiple windows, it's possible to avoid two mainloop()s. Thus, you can use the Toplevel() widget which is similar to Tk(). – Ky

Two mainloops doesn't "depend" on anything and it isn't just "looked down upon", it's flat out wrong. You only need one. A call to mainloop is an infinite loop, when you run more than one you have an infinite loop inside an infinite loop. You should remove the second call to mainloop in your code (in Demo1.new_window), otherwise it will be confusing to people who are trying to learn how to use Tkinter. – Butyraceous

Could you explain close_windows()? When does it have to be called? – Soundboard

@Soundboard close_window() is called when the "Quit" button of class Demo2 is clicked. Using the parameter command in tk.Button() creates this link. – Sticker

Is there a reason you decided against class Demo1() inheriting tk.Frame? – Darla

Answer 2

You need to specify the master for the second button. Otherwise it will get packed onto the first window. This is needed not only for Button, but also for other widgets and non-gui objects such as StringVar.

Quick fix: add the frame new as the first argument to your Button in Demo2.

Possibly better: Currently you have Demo2 inheriting from tk.Frame but I think this makes more sense if you change Demo2 to be something like this,

class Demo2(tk.Toplevel):     
    def __init__(self):
        tk.Toplevel.__init__(self)
        self.title("Demo 2")
        self.button = tk.Button(self, text="Button 2", # specified self as master
                                width=25, command=self.close_window)
        self.button.pack()

    def close_window(self):
        self.destroy()

Just as a suggestion, you should only import tkinter once. Pick one of your first two import statements.

Guppy

Answer 3

#!/usr/bin/env python
import Tkinter as tk

from Tkinter import *

class windowclass():

        def __init__(self,master):
                self.master = master
                self.frame = tk.Frame(master)
                self.lbl = Label(master , text = "Label")
                self.lbl.pack()
                self.btn = Button(master , text = "Button" , command = self.command )
                self.btn.pack()
                self.frame.pack()

        def command(self):
                print 'Button is pressed!'

                self.newWindow = tk.Toplevel(self.master)
                self.app = windowclass1(self.newWindow)

class windowclass1():

        def __init__(self , master):
                self.master = master
                self.frame = tk.Frame(master)
                master.title("a")
                self.quitButton = tk.Button(self.frame, text = 'Quit', width = 25 , command = self.close_window)
                self.quitButton.pack()
                self.frame.pack()


        def close_window(self):
                self.master.destroy()


root = Tk()

root.title("window")

root.geometry("350x50")

cls = windowclass(root)

root.mainloop()

Rainarainah

Answer 4

I tried to use more than two windows using the Rushy Panchal example above. The intent was to have the change to call more windows with different widgets in them. The butnew function creates different buttons to open different windows. You pass as argument the name of the class containing the window (the second argument is nt necessary, I put it there just to test a possible use. It could be interesting to inherit from another window the widgets in common.

import tkinter as tk

class Demo1:
    def __init__(self, master):
        self.master = master
        self.master.geometry("400x400")
        self.frame = tk.Frame(self.master)
        self.butnew("Window 1", "ONE", Demo2)
        self.butnew("Window 2", "TWO", Demo3)
        self.frame.pack()

    def butnew(self, text, number, _class):
        tk.Button(self.frame, text = text, width = 25, command = lambda: self.new_window(number, _class)).pack()

    def new_window(self, number, _class):
        self.newWindow = tk.Toplevel(self.master)
        _class(self.newWindow, number)


class Demo2:
    def __init__(self, master, number):
        self.master = master
        self.master.geometry("400x400+400+400")
        self.frame = tk.Frame(self.master)
        self.quitButton = tk.Button(self.frame, text = 'Quit', width = 25, command = self.close_windows)
        self.label = tk.Label(master, text=f"this is window number {number}")
        self.label.pack()
        self.quitButton.pack()
        self.frame.pack()

    def close_windows(self):
        self.master.destroy()

class Demo3:
    def __init__(self, master, number):
        self.master = master
        self.master.geometry("400x400+400+400")
        self.frame = tk.Frame(self.master)
        self.quitButton = tk.Button(self.frame, text = 'Quit', width = 25, command = self.close_windows)
        self.label = tk.Label(master, text=f"this is window number {number}")
        self.label.pack()
        self.label2 = tk.Label(master, text="THIS IS HERE TO DIFFERENTIATE THIS WINDOW")
        self.label2.pack()
        self.quitButton.pack()
        self.frame.pack()

    def close_windows(self):
        self.master.destroy()




def main(): 
    root = tk.Tk()
    app = Demo1(root)
    root.mainloop()

if __name__ == '__main__':
    main()

Open the new window only once

To avoid having the chance to press multiple times the button having multiple windows... that are the same window, I made this script (take a look at this page too)

import tkinter as tk


def new_window1():
    global win1
    try:
        if win1.state() == "normal": win1.focus()
    except:
        win1 = tk.Toplevel()
        win1.geometry("300x300+500+200")
        win1["bg"] = "navy"
        lb = tk.Label(win1, text="Hello")
        lb.pack()


win = tk.Tk()
win.geometry("200x200+200+100")
button = tk.Button(win, text="Open new Window")
button['command'] = new_window1
button.pack()
win.mainloop()

Insensate

Answer 5

What you could do is copy the code from tkinter.py into a file called mytkinter.py, then do this code:

import tkinter, mytkinter
root = tkinter.Tk()
window = mytkinter.Tk()
button = mytkinter.Button(window, text="Search", width = 7,
                               command=cmd)
button2 = tkinter.Button(root, text="Search", width = 7,
                               command=cmdtwo)

And you have two windows which don't collide!

Wymore

What a terrible idea. What about creating multiple windows dynamically? With your approach, you would then need to dynamically copy tkinter.py and add its copy to python path, then obtain proper classes from imported file, not to mention that in some cases you need to keep a reference to your UI elements somewhere so that GC won't get rid of them... no, just no. – Scotfree