Q250477: PRB: Terminate Events Fire in Reverse Order in VBCE/eVB

Article: Q250477
Product(s): Microsoft Visual Basic for Windows
Version(s): 3.0
Operating System(s): 
Keyword(s): kbToolkit kbVBp600 kbOSWinCE100 kbGrpDSVB
Last Modified: 05-APR-2002

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The information in this article applies to:

- Microsoft Windows CE Toolkit for Visual Basic 6.0 
- Microsoft eMbedded Visual Basic, version 3.0 
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SYMPTOMS
========

When two forms are shown and closed, the Terminate event of the second form
fires prior to the Terminate event of the first form. The order of these events
is opposite of what occurs in Microsoft Visual Basic 6.0. This behavior occurs
in the emulation environment and on the remote device.

RESOLUTION
==========

In cases where this behavior needs to be worked around, project level variables
can be used to store when forms in the project are loaded and unloaded. Each
form in the project can call a generic Terminate routine. When the generic
Terminate event is called and all forms that had been loaded have been unloaded,
the Terminate code can be executed.

The following example demonstrates this concept:

1. Create a new Windows CE project in either Visual Basic or eMbedded Visual
  Basic. Form1 is created by default.

2. Paste the following code into Form1:

  Private Sub Form_Click()
      Form2.Show
  End Sub

  Private Sub Form_Load()
      Form1Unloaded = False
  End Sub

  Private Sub Form_Terminate()
      TerminateHandler
  End Sub

  Private Sub Form_Unload(Cancel As Integer)
      Form1Unloaded = True
  End Sub

3. Add a second form to the project.

4. Paste the following code into Form2:

  Private Sub Form_Load()
      Form2Unloaded = False
  End Sub

  Private Sub Form_Terminate()
      TerminateHandler
  End Sub

  Private Sub Form_Unload(Cancel As Integer)
      Form2Unloaded = True
  End Sub

5. Add a module to the project.

6. Paste the following code into Module1:

  Dim Form1Unloaded
  Dim Form2Unloaded
  Dim ExecTerminateRoutine

  Sub TerminateHandler()
      If Form1Unloaded And Form2Unloaded And Not (ExecTerminateRoutine) Then
          ExecTerminateRoutine = True
          ' Execute termination code in
          ' the order required.
      End If
  End Sub

  Sub Main()
      Form1Unloaded = True
      Form2Unloaded = True
      ExecTerminateRoutine = False
      Form1.Show
  End Sub

7. In the Project Properties dialog box, change the Startup object to Sub Main.

8. Press the F5 key to run the program.

9. Click on Form1 and notice that Form2 is displayed.

10. Close Form2.

11. Close Form1.

12. After closing Form1, the TerminateHandler routine is called and the code
  within the If statement is executed once.

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

This behavior only occurs in the Windows CE Platform.

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

1. Start a new Windows CE Project in Visual Basic. Form1 is created by default.

2. On the Projects menu, select Components, and then select Microsoft CE File
  System Control.

3. Add a File control to Form1.

4. Paste the following code into Form1:

  Private Sub Form_Click()
      Form2.Show
  End Sub

  Private Sub Form_Terminate()
      File1.Open "terminate.txt", fsModeAppend
      File1.WriteFields "Form1 Terminate"
      File1.Close
  End Sub

5. Add a second form to the project.

6. Add a File control to Form2.

7. Add the following code behind Form2.

  Private Sub Form_Terminate()
      File1.Open "terminate.txt", fsModeAppend
      File1.WriteFields "Form2 Terminate"
      File1.Close
  End Sub

8. Press the F5 key to run the program.

9. Click on Form1 and note that Form2 is displayed.

10. Close Form2.

11. Close Form1.

12. Open the text file that has been created (terminate.txt) and note that the
  Terminate event of Form2 has been executed prior to the Terminate event of
  Form1.

Additional query words: wince vbce vbce6 eVB

======================================================================
Keywords          : kbToolkit kbVBp600 kbOSWinCE100 kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword2 kbVBeMbSearch kbWinCETKVBSearch kbWinCESearch kbVBeMb300
Version           : :3.0
Issue type        : kbprb

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