I'm trying to create a simple yes/no dialog box

[Larz60+]

Use tkinter.errormessage.askyesno
Here's a simple example:

import tkinter as tk
import tkinter.messagebox as tm


class Message:
    def __init__(self, parent=None):
        if parent is None:
            self.parent = tk.Tk()
        else:
            self.parent = parent

        result = self.show_error('Just a Message Box', 'My Message')
        print(result)

    def show_error(self, title, message):
        return tm.askyesno(title, message)

if __name__ == '__main__':
    Message()