FIX: Hide Event Doesn't Fire Correctly in Internet Explorer 4.0
ID: Q175907
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The information in this article applies to:
-
Microsoft Visual Basic Control Creation, Professional, and Enterprise Editions for Windows, version 5.0
-
Microsoft Internet Explorer (Programming) version 4.0
SYMPTOMS
Code placed in the Hide event of a UserDocument or a UserControl does not
execute under Internet Explorer 4.0. The Hide event does not fire correctly
for the following:
- ActiveX DLL UserDocument with Apartment-threading
- ActiveX DLL UserDocument with Single-threading and absence of Active
Desktop
- ActiveX Control OCX with Apartment-threading
- ActiveX Control OCX with Single-threading and absence of Active
Desktop
CAUSE
The Hide event is not getting fired for UserControl and UserDocument
objects because these objects are being released before receiving the Hide
event. Internet Explorer 3.0 does not have this problem because it
maintains a four-page cache. Internet Explorer 4.0 does not have a four-
page cache.
RESOLUTION
Add the following code to your UserDocument or UserControl module. The self-
reference will keep your object in memory long enough to receive the hide
event, at which point you can free the object reference:
- To the General/Declarations section of your code module, add:
Private objMe As Object
- To the UserDocument_Show or UserControl_Show event, add:
Set objMe = Me
- To the UserDocument_Hide or UserControl_Hide event, add:
Set objMe = Nothing
STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed
at the beginning of this article. This bug has been fixed in Visual Basic
6.0.
MORE INFORMATION
Steps to Reproduce Behavior
- Create a new ActiveX DLL project.
- From the Project properties, General, change threading model to be
"Apartment Threaded."
- Create a procedure to write debug messages to a file in your project
directory. Cut and paste the following code into your UserDocument:
Sub OutputDebug(iStr As String)
Dim H As Integer
H = FreeFile
Open App.Path + "\" + App.EXEName + "_Debug.TXT" For Append As #H
Print #H, iStr
Close #H
End Sub
- Add the following code to the Show and Hide events of your UserDocument:
Private Sub UserDocument_Hide()
OutputDebug "UserDocument_Hide"
End Sub
Private Sub UserDocument_Show()
OutputDebug "UserDocument_Show"
End Sub
- Save your project.
- Compile the ActiveX DLL. Go into the Project Properties, Component and
set Binary Compatibility to your ActiveX DLL.
- Save your project again.
- From Internet Explorer 4.0, navigate to .VBD file for your project. Wait
for your UserDocument to display.
- From Internet Explorer 4.0, navigate to a new location such as
www.microsoft.com.
- Exit Internet Explorer 4.0.
- Examine the PROJNAME_debug.txt file in your project directory. Note
that there is no Hide event message in the file. This indicates that the
Hide event was never fired.
Additional query words:
VBD Hide OCX KBiNETdEV kbVBp500bug kbIE400 kbdsi kbVBp600fix
Keywords :
Version :
Platform : WINDOWS
Issue type : kbbug