tkinter window fails to appear approx 10% of the time on MacOS 12.3+

Bug report

1 in 10 or 15 windows fails to appear when running tkinter on MacOS version 12.3+ and tkinter 8.6.12 using this simplified program:

import tkinter as tk

hmr = tk.Tk()
hmr.attributes('-alpha', 0)
hmr.withdraw()

root = tk.Toplevel(class_='toplevel')
root.attributes('-alpha', 0)

root.title('My Test Title')

frame = tk.Frame(root)
frame.pack(side=tk.TOP, anchor='nw', padx=0, pady=0, expand=False, fill=tk.NONE)
a = tk.Label(frame, text ="Hello World")
a.pack()

root.update_idletasks()
root.geometry("+600+600")
root.update_idletasks()
root.attributes('-alpha', 1)

root.mainloop()

Your environment

MacOS 12.3.1
Python 3.10.4
tkinter 8.6.12

Background

This problem was first reported to the PySimpleGUI project in mid-May. We've been working to find work-arounds and to narrow down the problem as much as possible. Because tkinter 8.6.11 isn't available pre-built on Python.org for 64 bit Macs, it's not been possible to test to see if 8.6.12 is the origin of the problem. While it is an intermittent problem, it's thankfully frequent enough to make duplication possible by running the program several times manually.

I assume it's an 8.6.12 problem as no one has reported the problem on 8.6.11 on any platform. Numerous MacOS users have been running into the problem.

The example code supplied is the most basic, shortest number of steps we've been able to create that perform the same operations that PySimpleGUI uses to build and move the window.

PySimpleGUI's default location for user windows is the center of the screen. So that users do not see the window "jump" from the starting location, the alpha channel is set to zero when the window is created and remains 0 while it's built and moved. Once moved into the final position, the Alpha channel is set to 1 and thus the window appears in the correct location without a visible jump.

Run the supplied tkinter reproducer repeatedly on macOS 12.3.1 with Python 3.10.4 and tkinter 8.6.12, observing whether the Toplevel window appears. Investigate the interaction between the alpha, withdraw, geometry, update_idletasks, and mainloop calls; done means the intermittent missing-window behavior is reproduced, explained, and no longer occurs under the reported environment.