Putting each of your top-level windows into it's own separate class gives you code re-use and better code organization. Any buttons and relevant methods that are present in the window should be defined inside this class. Here's an example (taken from here):
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()
Also see:
- simple hello world from tkinter docs
- Tkinter example code for multiple windows, why won't buttons load correctly?
- Tkinter: How to Show / Hide a Window
Hope that helps.