FIX: Application Error When Binding Dynamically-Created Control

• Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 32-bit only, for Windows, version 4.0

SYMPTOMS

An application error occurs when a Visual Basic program dynamically creates a text box bound to a remote data control or a data control.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been corrected in Visual Basic, version 5.0.

MORE INFORMATION

This section shows you how to reproduce the bug in Visual Basic 4.0 using a data control. You can substitute a remote data control for a data control and still reproduce the behavior.

Steps to Reproduce Behavior

1. Start 32-bit Visual Basic 4.0 or, if it is already running, click New Project on the File menu.

2. Add the following controls to Form1 and set the following properties to the appropriate controls:

      Control           Default Name     Property            Setting
      ---------------------------------------------------------------
      Command Button    Command1
   
      Data              Data1            DatabaseName        Biblio.mdb
                                         RecordSource        Authors
   
      Text Box          Text1            DataSource          Data1
                                         Index               0
   
   

3. Copy the following code to the Code window of Form1:

         Option Explicit
   

         Private Sub Form_Load()
            Command1.Caption = "For Remote Data Control"
         End Sub
   
         Private Sub Command1_Click()
            Dim count As Integer
            Dim i As Integer
            Static lastcount As Integer
   
            Data1.Refresh
            count = 4
   
            If lastcount > 0 Then
               For i = lastcount - 1 To 1 Step -1
                  Unload text1(i)
               Next i
            End If
   
            If count > 0 Then
               For i = 1 To count - 1
                  Load text1(i)
                  text1(i).Left = text1(0).Left + (i * 1335)
                  text1(i).Visible = True
               Next i
            End If
            lastcount = count
         End Sub
   
   

4. On the Run menu, click Start or press the F5 key to start the program. Each time you click the command button, three text boxes appear. On the third click, an application error occurs displaying one of the following messages and Visual Basic ends:

   Windows NT 3.51:

         An application error has occurred and an application error log is
         being generated.VB32.exe.
         Exception: access violation (0xc0000005), Address: 0x00402a38
   

   Windows 95:

         VB32 caused an invalid page fault in module VB32.EXE at
         0137:00402a3a.
   

         -and-
   

         VB32 caused an invalid page fault in module KERNEL32.DLL at
         0137:bff9a07c.