Re: Parent and Child in separate UI Threads

"Doug Harrison [MVP]" <>
Tue, 27 May 2008 10:16:53 -0500
On Tue, 27 May 2008 07:24:00 -0700, Denis Adamchuk
<> wrote:

Well, we have an EXE module and DLL module.
EXE is an MDI MFC application and it uses Doc/View architecture.
DLL contains business logic, some MFC windows and some dialogs.
EXE collaborates with DLL via interface described by IDL (but it is not COM).
So one of the views in EXE is a parent of windows from DLL. The view is like
a container.
The goal is to make all DLL stuff to work in a separate thread.
It will have a message-only window that will receive messages from the main
thread (IDL wrapped calls) and place them to the DLL's thread message queue...
So we have to make a UI thread in DLL and create there all windows DLL

I believe that under the hood, COM uses a hidden window and interthread
SendMessage to do what you're describing. A thread stuck waiting on
SendMessage to complete can still dispatch interthread SendMessage calls to
it, so it's not as deadlock-prone as you might think.

If you still want to spread your windows over different threads, I'm not
sure how that will interact with doc/view, but there is this MFC example
for an MDI program, so it would seem to be possible for simpler cases at

MTMDI Sample: Demonstrates an MFC User Interface Thread

Doug Harrison
Visual C++ MVP

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