Q257686: FIX: Double-Clicking ListBox Control Causes Invalid Page Fault

Article: Q257686
Product(s): Microsoft Visual Basic for Windows
Version(s): 6.0
Operating System(s): 
Keyword(s): kbCtrl kbListBox kbVBp kbVBp600bug kbOSWin95 kbOSWin98 kbGrpDSVB kbDSupport kbVS600sp4f
Last Modified: 28-JUL-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, version 6.0, on platform(s):
   - the operating system: Microsoft Windows 95 
   - the operating system: Microsoft Windows 98 
   - the operating system: Microsoft Windows Millennium Edition 
- Microsoft Visual Basic Professional Edition for Windows, version 6.0, on platform(s):
   - the operating system: Microsoft Windows 95 
   - the operating system: Microsoft Windows 98 
   - the operating system: Microsoft Windows Millennium Edition 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0, on platform(s):
   - the operating system: Microsoft Windows 95 
   - the operating system: Microsoft Windows 98 
   - the operating system: Microsoft Windows Millennium Edition 
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SYMPTOMS
========

In a case where you have a form with a ListBox control and you are populating
the list from a database, if you unload the form in the double-click event of
the ListBox control, an Invalid Page Fault occurs.

STATUS
======

Microsoft has confirmed that this is a bug in the Microsoft products that are
listed at the beginning of this article. This bug was corrected in the latest
service pack for Visual Studio 6.0.

For additional information about Visual Studio service packs, click the following
article numbers to view the articles in the Microsoft Knowledge Base:

  Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

  Q194295 HOWTO: Tell That a Visual Studio Service Pack Is Installed

To download the latest Visual Studio service pack, visit the following Microsoft
Web site:

  http://msdn.microsoft.com/vstudio/downloads/updates.asp

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

The following steps use the Biblio database. They assume that the database is
located in the default Visual Basic installation path:

C:\Program Files\Microsoft Visual Studio\Vb98\Biblio.mdb

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

1. Start a new Standard EXE project in Visual Basic. Form1 is created by
  default.

2. On the Project menu, select References. On the References dialog box, check
  Microsoft ADO 3.51 Object Library, and then click OK.

3. On the Project menu, add a new module, and then insert the following code:

  Option Explicit

  Public MainDatadb As Database

4. Add a Command Button to Form1.

5. Add the following code to the code window of Form1:

  Option Explicit

  Private Sub Command1_Click()
      Form2.ShowMeGeneral MainDatadb, "Authors", "Author", "AU_id", , _
        "Find an author", "au_id"
  End Sub

  Private Sub Form_Load()
      Dim DBName As String

      ' Change the following path if necessary for your system
      DBName = "C:\Program Files\Microsoft Visual Studio\VB98\BIBLIO.MDB"
      Set MainDatadb = OpenDatabase(DBName, False, False)
  End Sub

6. On the Project menu, add a second form, Form2, to the project.

7. Add a ListBox control to Form2.

8. Add the following code to the code window of Form2:

  Option Explicit

  Public SelectedValue As String
  Public KeyValue As String
  Public Canceled As Boolean

  Public Sub ShowMeGeneral(DBName As Database, DBTable As String, _
   FldDisplay As String, FldReturn As String, Optional InSql As Variant, _
   Optional Title As Variant, Optional KeyField As Variant)

      Dim Sql As String, TempRS As Recordset
      Dim Indx As Integer, TmpString As String
      Dim DisplayString As String
      If IsMissing(InSql) Then
          Sql = "SELECT [" & FldDisplay & "],[" & FldReturn & "] " & _
          "FROM " & DBTable & " ORDER BY [" & FldDisplay & "];"
      Else
          Sql = InSql
      End If
      Set TempRS = DBName.OpenRecordset(Sql, , dbReadOnly)
      Do Until Indx > 5000
          DisplayString = TempRS(FldDisplay) & ""
          DisplayString = "abcdefghijklmm" & Indx
          List1.AddItem DisplayString
          Indx = Indx + 1
          TempRS.MoveNext
      Loop
      TempRS.Close
      Set TempRS = Nothing
      List1.ListIndex = 0
      Canceled = True
      Me.Show vbModal
  End Sub

  Private Sub List1_DblClick()
      Unload Me
  End Sub

9. Run the project and click on Command1 to open Form2.

10. Double-click on an item in the ListBox control on Form2.

The result should be an Invalid Page Fault.

Additional query words: sp4 IPF GPF

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Keywords          : kbCtrl kbListBox kbVBp kbVBp600bug kbOSWin95 kbOSWin98 kbGrpDSVB kbDSupport kbVS600sp4fix kbVS600sp5fix 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2
Version           : :6.0
Issue type        : kbbug
Solution Type     : kbfix

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