Py2app tkinter 'Discovered a lack of restrictions

Question

I am trying to pack an existing python script that uses tk to select a file and requests a value in an application that includes all the dependencies.

I am using MacOS 10.12.5, homebrew python 3.6.1 and py2app 0.14.

The following works fine as a script, but when it is converted to an application (or an Alias ​​application), I get an error message Detected missing constraints for <private>...on the console. A simplified version that still causes the same error:

#!/usr/bin/env python3
# encoding: utf-8

import tkinter as tk
from tkinter import simpledialog

root = tk.Tk()
root.withdraw()

the_answer = simpledialog.askstring("Input", "What is the answer?",)

Am I missing something or is this a mistake? If this is an error, is it a tk or py2app error?