This is an old problem that was solved for Python 2.7. From Python 3.8 on, the behavior is the same with Python 3. The fix finally was to extend a Python 2.7 patch to Python 3 as well. See the Jira issue for details. Other little changes: This patch includes also a small patch that was mentioned as necessary for Python 3.9: Python issue 40217. I have seen no effect of this change yet but applied the patch, anyway. When searching for a solution of this problem, a lot of time was spent debugging qapp_macro.cpp, although it was error-free. As a side effect for better understanding, the variables were renamed to more common style. These more independent changes could have got their own check-in, but the complication of a pick-to and the small code size wasn't worth the effort. Change-Id: I7638f1a711315b4678af6b7389265b905c6404a1 Fixes: PYSIDE-1447 Reviewed-by: Dmitry Shachnev <mitya57@gmail.com> Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io> (cherry picked from commit c1f776570adbe4f9aa21aa818a82f5ebd1258a76) Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>