Tkinter messageboxes opened from a pystray menu appear unfocused or behind other windows on Windows 11

I'm building a Python desktop app that uses both pystray (for a system tray icon) and Tkinter (for message boxes and dialogs). Everything works fine except for one issue on Windows 11: when I open a tkinter.messagebox (or any Tkinter window) from a pystray menu callback, the window appears unfocused or behind other windows

Note that my program works on Windows 10.

What I’ve tried

• Setting root.attributes("-topmost", True) and root.focus_force()

• Calling root.lift() or root.after() to delay focus

• Running Tk() in the main thread

• Using a dedicated GuiDispatcher class to marshal UI calls to the main Tkinter thread

The problem persists intermittently — sometimes it works, sometimes the window still opens in the background.

System info

• Windows 11 23H2

• Python 3.13

• pystray 0.19.5

• tkinter (standard)

What I’d like to know

• Is this a known limitation or bug with Tkinter on Windows 11 when invoked from non-main threads?

• Any best practices for combining pystray and Tkinter in multi-threaded apps?

Here's a minimal reproducible example:

import threading
import tkinter as tk
from tkinter import messagebox
import pystray
from PIL import Image, ImageDraw

def create_icon_image():
    img = Image.new('RGB', (64, 64), (30, 144, 255))
    d = ImageDraw.Draw(img)
    d.rectangle([16, 16, 48, 48], fill=(255, 255, 255))
    return img

def show_messagebox():
    root = tk.Tk()
    root.withdraw()
    messagebox.showinfo("Test", "Window opened from tray menu", parent=root)
    root.destroy()

def on_click(icon, item):
    threading.Thread(target=show_messagebox, daemon=True).start()

icon = pystray.Icon(
    "test_icon",
    create_icon_image(),
    "Test Tray",
    menu=pystray.Menu(pystray.MenuItem("Show message", on_click))
)

icon.run()