FIX: Double-Clicking ListBox Control Causes Invalid Page Fault

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.

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

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.