Q190220: PRB: "Invalid Property Value" When You Query MDIChild Property

Article: Q190220
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:5.0
Operating System(s): 
Keyword(s): kbcode kberrmsg kbnokeyword kbVBp500 kbVBp600 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
========

In Visual Basic, if you query for the MDIChild property of an MDI Parent form,
the following error occurs:

  Error 380 : Invalid Property Value

CAUSE
=====

MDI Parent forms do not have an MDIChild property. To query for this nonexistent
property will result in the above error.

RESOLUTION
==========

To resolve this, use the following code to query for the MDIChild property of a
form:

Sample Code
-----------

     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
======

This behavior is by design.

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

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

1. Create a new Standard EXE project in Visual Basic.

2. Add an MDI form to the project by selecting Add MDI Form from the Project
  menu.

3. Set the MDIChild property of Form1 to True.

4. Paste the following code in the General Declarations section of Form1:

        Private Sub Form_Click()
           Dim f As Form
           For Each f In Forms
              If f.MDIChild Then
                 Form1.Print f.Name & "   MDI Child"
              Else
                 Form1.Print f.Name & "   Not MDI Child"
              End If
           Next
        End Sub

5. Press F5 to run the project

6. Click on Form1.

An error message displays "Run-Time Error 380 : Invalid Property Value" instead
of printing all of the names of the forms, and a value indicating whether or not
they are an MDI Child form

Additional query words:

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Keywords          : kbcode kberrmsg kbnokeyword kbVBp500 kbVBp600 kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600
Version           : WINDOWS:5.0
Issue type        : kbprb

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