DOCUMENT:Q168831  11-JAN-2001  [vbwin]
TITLE   :PRB: Older MFC OCX Controls Incompatible with Visual Basic 4.0
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:
OPER/SYS:
KEYWORDS:kbGrpDSVBDB

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The information in this article applies to:

 - Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
 - Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
 - Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
 - Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
 - Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SYMPTOMS
========

Upon placing an OCX control on a Visual Basic form, the control will ASSERT or
cause a General Protection Fault. The most common asserts are as follows:

 - Assertion Failure in CTLPROP.CPP Line 768

 - Assertion Failure in CTLMODUL.CPP Line 128

The control will continue to run in most cases, but will not function properly.

CAUSE
=====

OLE Custom Controls (OCX Controls) created using the Microsoft Foundation
Classes (MFC) that ship with Microsoft Visual C++ version 2.0 or earlier for
32-bit development and Microsoft Visual C++ 1.51 or earlier for 16-bit
development will not work properly in Visual Basic 4.0.

The OCX standards and implementations have changed such that some minor
incompatibilities have been created. The following MFC code raises the assertion
when Visual Basic passes NULL as parameters:

      STDMETHODIMPCOleControl::XPerPropertyBrowsing::GetPredefinedStrings(
          DISPID dispid,
      CALPOLESTR FAR* lpcaStringsOut, CADWORD FAR*
       lpcaCookiesOut)
      {
          ...
          METHOD_MANAGE_STATE(COleControl,PerPropertyBrowsing)
          ...
          ASSERT_POINTER(lpcaStringsOut,CALPOLESTR);
          ASSERT_POINTER(lpcaCookiesOut, CADWORD);
          ...
      }

RESOLUTION
==========

Upgrade to Visual C++ 2.1 or higher for 32-bit development and Visual C++ 1.52
or higher for 16-bit development.

STATUS
======

Microsoft has confirmed this to be a problem with Visual C++ version 2.0 and
earlier for 32-bit development and Visual C++ 1.51 and earlier for 16-bit
development.

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Troy
Cambra, Microsoft Corporation


Additional query words: kbMFC kbVBp400 kbdse kbDSupport kbVBp kbVC

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Keywords          : kbGrpDSVBDB 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Issue type        : kbprb

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