DOCUMENT:Q140492  06-MAY-2001  [visualc]
TITLE   :PRB: Possible Recursion Problems with OLE Controls
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:4.0
OPER/SYS:
KEYWORDS:kbActiveX kbCOMt kbCtrlCreate kbMFC kbVC400 kbGrpDSMFCATL

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - The Microsoft Foundation Classes (MFC), used with:
    - Microsoft Visual C++, 32-bit Editions, version 4.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Attempting to use an OLE control in the same module that implements it may
generate an exception caused by a stack overflow. One example of using an OLE
control in this manner is placing an instance of an OLE control in that same OLE
control's About dialog box.

CAUSE
=====

Calling certain CWnd members can create an infinitely recursive loop, causing a
stack overflow to occur.

RESOLUTION
==========

Avoid calling certain CWnd members when using an OLE control in the same module
that implements it.

STATUS
======

This behavior is by design.

MORE INFORMATION
================

The COleControl class itself has been written to make sure that its members are
safe and can be called even when a control is being used in the module that
implements it. However, certain CWnd members are not safe to call when a control
is being used in this fashion. CWnd members that can cause problems include
ShowWindow, MoveWindow, SetWindowPos, EnableWindow, SetWindowText,
GetWindowText, and GetWindowTextLength.

There may be other members that can cause the same problem. If a control is being
used in the same module that implements it and a stack overflow occurs, the
first thing the control programmer should check for is this problem.

Additional query words: 4.00

======================================================================
Keywords          : kbActiveX kbCOMt kbCtrlCreate kbMFC kbVC400 kbGrpDSMFCATL 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:4.0
Issue type        : kbprb

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.