[python-win32] HookMessage fails

[TK Soh]

Greeting.

I built a custom dialog which would be resized by a handler connected
with HookMessage() to win32con.WM_SIZE. The dialogs are actually
called from the shell extension's context menu. Every seemed to work
well at first.

The I noticed the resize handler is only called on the dialogs that
are called from the explorer window that made the first call. The same
dialogs that are called from other explorer windows seemed to have the
handler ignored. In fact I did some experiment indicating that the
problem is not unique to WM_SIZE, but any handlers that are hooked by
HookMessage.

Appreciate if anyone can help shed some light on this. Thanks.