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Q171834: FIX: Crash When UserControl Accesses Members of ParentControls

Article: Q171834
Product(s): Microsoft Visual Basic for Windows
Version(s): 5.0
Operating System(s): 
Keyword(s): kbVBp500 kbVS97sp2fix kbGrpDSVB kbvbp500sp2fix
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Control Creation Edition for Windows, version 5.0 
- Microsoft Visual Basic Learning Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
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SYMPTOMS
========

When a UserControl tries to access members of the ParentControls collection when
it is not in UserMode (AmbientProperties.UserMode = False), the following error
may occur:

  "VB5 caused an invalid page fault in module VB5.EXE at 0137:004650a3."

CAUSE
=====

Visual Basic 5.0 is not releasing the interfaces correctly.

RESOLUTION
==========

Install Visual Studio 97 Service Pack 2 (SP2). Alternately, use a For...Next
loop instead of a For...Each loop when looping through the ParentControls
collection to avoid the error.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug has been fixed in Visual Studio 97 Service
Pack 2.

For more information on the Visual Studio 97 Service Pack 2, please see the
following article in the Microsoft Knowledge Base:

  Q170365 : INFO: Visual Studio 97 Service Packs - What, Where, and Why

For a list of the Visual Basic 5.0 bugs that were fixed in the Visual Studio 97
Service Pack 2, please see the following article in the Microsoft Knowledge
Base:

  Q171554 : INFO: Visual Basic 5.0 Fixes in Visual Studio 97 Service Pack 2

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

Steps to Reproduce Behavior
---------------------------

1. Create a new Visual Basic 5.0 ActiveX Control project.

2. Add a Label control to the UserControl.

3. Add the following code to the UserControl:

        Public Property Let TheLoop(bLoop As Boolean)
           Dim oObject As Object
           Dim sName As String
           For Each oObject In ParentControls
               sName = oObject.Name
               Debug.Print sName
           Next
        End Property

        Public Property Get TheLoop() As Boolean

        End Property

4. Select File...Add Project from the menu bar and add a Standard EXE project.

5. Place an instance of UserControl1 (UserControl11) on Form1.

6. Place three or four other controls on Form1.

7. Select UserControl11 and change the TheLoop property.

8. Repeat step 7. Note that an invalid page fault in Visual Basic results.

Additional query words: kbDSupport

======================================================================
Keywords          : kbVBp500 kbVS97sp2fix kbGrpDSVB kbvbp500sp2fix 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500Search kbVBA500 kbVB500 kbZNotKeyword3
Version           : 5.0
Issue type        : kbbug
Solution Type     : kbfix

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

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