FIX: Memory Leak with Command Button on Japanese Windows 95C (OSR 2.5)

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, versions 5.0, 6.0

SYMPTOMS

A memory leak might occur on Japanese Windows 95C (OSR 2.5) when unloading a Form that contains a CommandButton.

CAUSE

This problem occurs when the CommandButton's TabIndex property = "0" and its TabStop property = "TRUE."

RESOLUTION

Set the TabIndex of the CommandButton to a value greater than 0.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

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

Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

MORE INFORMATION

Steps to Reproduce Behavior

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



2. Add a CommandButton and Timer control to Form1.



3. Add the following code to the General Declarations section of Form1:




Option Explicit
Private f As Boolean

Private Sub Command1_Click()
   Timer1.Enabled = True
End Sub

Private Sub Form_Load()
   Timer1.Interval = 500
   Timer1.Enabled = False
End Sub

Private Sub Timer1_Timer()
   f = Not f
   If f Then
      Form2.Show
   Else
      Unload Form2
      Set Form2 = Nothing
   End If
End Sub 

4. On the Project menu, click Add Form to add a new form to the project. Form2 is created by default.



5. Add a CommandButton to Form2.



6. Compile the Application to an EXE file.



7. Run the compiled EXE on Japanese Windows 95C.



8. Start the System Monitor tool, which is located in the System Tools folder in the Accessories folder. (If the System Monitor tool is not available, it can be installed from the Control Panel Add/Remove Programs option.) On the Edit menu, click Add Item. Click the Memory Manager Category, click the Allocated Memory Item, and click OK.



9. Click Command1 to start loading/unloading Form2.
   
   Result: The "Allocated Memory" will steadily increase as the application is running and might eventually cause the application to crash.

Additional query words:

Keywords          : kbservicepack kbFarEast kbIntl kbOSR250 kbVBp kbVBp500bug kbVBp600bug kbWinOS95 kbGrpVB kbVS600sp2 kbVS600SP1 kbVS600sp3fix 
Version           : WINDOWS:5.0,6.0
Platform          : WINDOWS 
Issue type        : kbbug 

Last Reviewed: May 19, 1999