Patrick Rutkowski added the comment:
I removed my custom built Python and installed the one provided by the
python-3.6.2-amd64.exe installer instead.
The Win32 Command Line application now works, and shows the message box. The
Win32 GUI Application still fails to work, the output is just nothing. As
expected, pythonw works as always, it shows the popup.
Python tracker <rep...@bugs.python.org>
Python-bugs-list mailing list