Q176429: BUG: Can’t Check MDIChild Property of Forms in Forms Collection

Article: Q176429
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): kberrmsg kbnokeyword kbVBp500bug kbVBp600bug kbGrpDSVB
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
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SYMPTOMS
========

The following code worked in Visual Basic 4.0, but fails in Visual Basic 5.0 or
6.0 with an error "Error 380, Invalid Property Value" if an MDI parent form is
in the project:

     Dim f As Form
        For Each f In Forms
          If Not TypeOf f Is MDIForm Then
            If f.MDIChild Then
              Form1.Print f.Name & "   MDI Child"
            Else
              Form1.Print f.Name & "   Not MDI Child"
            End If
          Else
            Form1.Print f.Name & "  Not MDI Child"
          End If
        Next

CAUSE
=====

MDI forms do not have a MDIChild property in Visual Basic 4.0, 5.0, or 6.0.
Visual Basic 4.0 compensated for that in the specific case of looping through
the forms collection and checking this property, but Visual Basic 5.0 and 6.0 do
not.

RESOLUTION
==========

The workaround is to determine if the form is an MDI form before checking the
MDIChild property, which the following code demonstrates:

     Dim f As Form
     For Each f In Forms
       If Not TypeOf f Is MDIForm Then
         If f.MDIChild Then
           Form1.Print f.Name & "   MDI Child"
         Else
           Form1.Print f.Name & "   Not MDI Child"
         End If
       Else
         Form1.Print f.Name & "  Not MDI Child"
       End If
     Next

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. We are researching this bug and will post new
information here in the Microsoft Knowledge Base as it becomes available.

Additional query words:

======================================================================
Keywords          : kberrmsg kbnokeyword kbVBp500bug kbVBp600bug kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600
Issue type        : kbbug

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