KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q148616: FIX: DisplayAsDefault Ambient Property Not Updated for Control

Article: Q148616
Product(s): Microsoft C Compiler
Version(s): winnt:
Operating System(s): 
Keyword(s): kbole kbActiveX kbCOMt kbContainer kbCtrl kbLocalSvr kbMFC kbVC400bug kbVC410fix kbGrpD
Last Modified: 06-MAY-2001

-------------------------------------------------------------------------------
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

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

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.