gh-118293: Suppress mouse cursor change in multiprocessing

tunedal · tunedal · commit 47b41806510a · 2024-04-26T14:30:32.000+02:00
diff --git a/Lib/multiprocessing/popen_spawn_win32.py b/Lib/multiprocessing/popen_spawn_win32.py
@@ -3,6 +3,7 @@
 import signal
 import sys
 import _winapi
+from subprocess import STARTUPINFO
 
 from .context import reduction, get_spawning_popen, set_spawning_popen
 from . import spawn
@@ -18,6 +19,7 @@
 TERMINATE = 0x10000
 WINEXE = (sys.platform == 'win32' and getattr(sys, 'frozen', False))
 WINSERVICE = sys.executable.lower().endswith("pythonservice.exe")
+STARTF_FORCEOFFFEEDBACK = 0x80
 
 
 def _path_eq(p1, p2):
@@ -74,7 +76,8 @@ def __init__(self, process_obj):
             try:
                 hp, ht, pid, tid = _winapi.CreateProcess(
                     python_exe, cmd,
-                    None, None, False, 0, env, None, None)
+                    None, None, False, 0, env, None,
+                    STARTUPINFO(dwFlags=STARTF_FORCEOFFFEEDBACK))
                 _winapi.CloseHandle(ht)
             except:
                 _winapi.CloseHandle(rhandle)
diff --git a/Misc/NEWS.d/next/Windows/2024-04-26-14-23-07.gh-issue-118293.ohhPtW.rst b/Misc/NEWS.d/next/Windows/2024-04-26-14-23-07.gh-issue-118293.ohhPtW.rst
@@ -0,0 +1,2 @@
+The `multiprocessing` module now passes the `STARTF_FORCEOFFFEEDBACK` flag
+when spawning processes to tell Windows not to change the mouse cursor.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	+The `multiprocessing` module now passes the `STARTF_FORCEOFFFEEDBACK` flag
	`2`	`+when spawning processes to tell Windows not to change the mouse cursor.`