Get current app window handle and bring window to front

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Python

management

I'm trying to set up a simple command line chat application between two computers on my home network. I have the server and client scripts working exactly the way I want except for one little thing. At least, it should be little and I do not understand why it is so difficult.

I intend to leave the script running in a small window. When it receives a new message, I want it to pop to the front. When I comment out the line that does this, the script works. But when I enable the "to front" line, it aborts with

Exception in thread Thread-2 (recv_message):
Traceback (most recent call last):
  File "C:\Python\lib\threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "C:\Python\lib\threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "D:\apps\chat\client.py", line 30, in recv_message
    win32gui.SetForegroundWindow(hwnd)
pywintypes.error: (0, 'SetForegroundWindow', 'No error message is available')

I've tested the code for win32gui.SetForegroundWindow(hwnd) by starting two client apps and, from a Python shell, running win32gui.SetForegroundWindow(hwnd) with (in turn) both of the handles. No problem. Until I enable the code in the client script. When I do that, I get the exception. I am running Python 3.10.11 on Windows 11 Home.

Here is the client script:

  1  import socket
  2  import threading
  3  import win32gui
  4  import ctypes
  5  
  6  host = 'jim-asus'
  7  port = 1234
  8  hwnd = ctypes.windll.user32.GetForegroundWindow()
  9  
 10  server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 11  server.connect((host, port))
 12  
 13  print(f'Connected to the server. {hwnd=}')
 14  
 15  def send_message():
 16      
 17      while True:
 18          message = input('')
 19          server.send(message.encode())
 20  
 21  def recv_message():
 22      
 23      while True:
 24          message = server.recv(1024)
 25          print(">>", message.decode())
 26          print(f'set {hwnd=} to front')
 27          win32gui.SetForegroundWindow(hwnd)
 28  
 29  send = threading.Thread(target=send_message)
 30  recv = threading.Thread(target=recv_message)
 31  
 32  send.start()
 33  recv.start()

What I have tried:

pywin32, AutoItX, win32gui, pywinauto