BUG: Type Mismatch Error When Calling ShowBrowserBar Without Optional Parameter

Calling the InternetExplorer object's ShowBrowserBar method without the optional second parameter (pvarShow) produces the following error message: The same error occurs if Null (or 0 or vbNull or vbNullString) is used for the second parameter.

ShowBrowserBar does not check for the variant types VT_ERROR and VT_NULL (passed by a missing parameter and the Visual Basic keyword Null, respectively) when determining the validity of the pvarShow parameter.

The second parameter must be present and must be declared as a variant having one of three values: true, false, or empty (an uninitialized variant). Note that passing empty has the same effect as passing true, since the default action is to show the bar.

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

Steps to Reproduce Behavior

1. Start a new Standard EXE project in Visual Basic. Form1 is created by default.
2. Add a reference to the Microsoft Internet Controls (Shdocvw.dll) using References on the Project menu.
3. Copy the following code into the Code window of Form1:

   Dim WithEvents g_ieAuto As InternetExplorer
   
   Private Sub Form_Load()
      Set g_ieAuto = New InternetExplorer
      g_ieAuto.Visible = True
      g_ieAuto.Navigate2 "http://msdn.microsoft.com/workshop"
   End Sub
   
   Private Sub g_ieAuto_DocumentComplete(ByVal pDisp As Object, URL As Variant)
      g_ieAuto.ShowBrowserBar "{30D02401-6A81-11D0-8274-00C04FD5AE38}"
   End Sub
   					

4. On the Run menu, click Start or press the F5 key to start the program. The error message will appear.
5. Change the call to ShowBrowserBar to the following:

      g_ieAuto.ShowBrowserBar "{30D02401-6A81-11D0-8274-00C04FD5AE38}", Empty
   					

6. On the Run menu, click Start, or press the F5 key to start the program. The error message does not appear and the Search bar is displayed.

For additional information, please see the following MSDN Web Workshop site: