DOCUMENT:Q148616  06-MAY-2001  [visualc]
TITLE   :FIX: DisplayAsDefault Ambient Property Not Updated for Control
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:
OPER/SYS:
KEYWORDS:kbole kbActiveX kbCOMt kbContainer kbCtrl kbLocalSvr kbMFC kbVC400bug kbVC410fix kbGrpD

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

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

SYMPTOMS
========

When you use the arrow keys to change between controls in a Visual C++ 4.0
generated container, the DISPID_AMBIENT_DISPLAYASDEFAULT ambient property of the
control site is not updated, and any control that relies on this property
doesn't function correctly.

For example, a subclassed button control that is programmed to update its border
according to the DISPID_AMBIENT_DISPLAYASDEFAULT ambient property will exhibit
this behavior. In a Visual C++ generated container, the control won't update its
border.

CAUSE
=====

In Occdlg.cpp, the following line 542 shouldn't be called:

        bCheckDef = FALSE;

This line keeps CheckDefPushButton from being called and the ambient property
from being updated.

RESOLUTION
==========

The best solution is to upgrade to Visual C++ 4.1. If this is not a possibility,
the MFC DLL can be rebuilt without bCheckDef = FALSE; however, Microsoft
recommends against this because you need to rebuild the DLL with a different
name (see tech note 33).

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This problem was corrected in Microsoft Visual C++
version 4.1.

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

Sample Code
-----------

The following code can be added to the Button Control sample shipped with Visual
C++ to demonstrate this problem.

   /////////////////////////////////////////////////////////////////////////// 
   / 
   // Display the button with a thick border if appropriate

   void CButtonCtrl::OnAmbientPropertyChange(DISPID dispid)
   {
       TRACE("OnAmbientPropertyChange called\n");
       BOOL bDisplayAsDefault = FALSE;
       if(DISPID_AMBIENT_DISPLAYASDEFAULT != dispid)
           return;
       // Check the control site to see if you should add or remove the border
       if (!GetAmbientProperty(DISPID_AMBIENT_DISPLAYASDEFAULT, VT_BOOL,
               &bDisplayAsDefault))
           ASSERT(FALSE);
       if(bDisplayAsDefault)
           SendMessage(BM_SETSTYLE, BS_DEFPUSHBUTTON, 0);
       else
           SendMessage(BM_SETSTYLE, BS_PUSHBUTTON, 0);
       InvalidateControl();
   }

Additional query words: 4.00 focus

======================================================================
Keywords          : kbole kbActiveX kbCOMt kbContainer kbCtrl kbLocalSvr kbMFC kbVC400bug kbVC410fix kbGrpDSMFCATL kbNoUpdate kbbuglist kbfixlist
Technology        : kbAudDeveloper kbMFC
Version           : winnt:
Issue type        : kbbug
Solution Type     : kbfix

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

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