Microsoft KB Archive/173638

= BUG: "What's This?" Button Disappears from MDI Child Forms =

Article ID: 173638

Article Last Modified on 12/10/2003

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APPLIES TO


 * Microsoft Visual Basic 5.0 Control Creation Edition
 * Microsoft Visual Basic 5.0 Learning Edition
 * Microsoft Visual Basic 5.0 Professional Edition
 * Microsoft Visual Basic 5.0 Enterprise Edition

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This article was previously published under Q173638



SYMPTOMS
Setting both the WhatsThisButton property and the WhatsThisHelp property of an MDI child form to True does not enable the What's This button to appear in the title bar of the form.



RESOLUTION
According to the Help for Visual Basic 5.0, the What's This? button will appear in the title bar of a form when the WhatsThisHelp property and the WhatsThisButton property are both set to True and the following properties are also set as shown: ControlBox = True

MinButton = False and/or MaxButton = False BorderStyle = 1 - Fixed Single or BorderStyle = 2 - Sizable Or  BorderStyle = 3 - Fixed Dialog However, the What's This? button fails to appear in the title bar of an MDI child form even when the conditions above are met.

To work around this problem, you can use the Windows SetParent API to make one form the child of another and create the illusion of an MDI form in which the What's This button is functional.

Step-by-Step Instructions
 Start a new Standard EXE project. Form1 is added by default. Add another form (Form2) to the project.  Set the following properties of Form2: MaxButton = False MinButton = False WhatsThisButton = True WhatsThisHelp = True   Insert the following code to Form1's General Declarations section: Private Declare Function SetParent Lib "user32" _ (ByVal hWndChild As Long, ByVal hWndNewParent As Long) As Long

Private Declare Function GetWindowLong Lib "user32" _ Alias "GetWindowLongA" _ (ByVal hwnd As Long, ByVal nIndex As Long) As Long Private Declare Function SetWindowLong Lib "user32" _ Alias "SetWindowLongA" _ (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) _ As Long

Const WS_CHILDWINDOW = &H40000000 Const GWL_STYLE = (-16)   Insert the following code to Form1's Load event procedure: Private Sub Form_Load Dim x As Long Dim y As Long 'Set Form1 as the parent of form2 x = SetParent(Form2.hwnd, Form1.hwnd) Form2.Show

x = GetWindowLong(Form2.hwnd, GWL_STYLE) y = x + WS_CHILDWINDOW x = SetWindowLong(Form2.hwnd, GWL_STYLE, y)     End Sub  Press the F5 key to run the program. You will see Form2 acting as Form1's child with a What's This? Button on its toolbar.</ol>

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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.

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Steps to Reproduce Behavior
<ol> Start a new Standard EXE project. Form1 is added by default.</li> Add a MDI form (MDIForm1) to the project.</li>  Set the following properties of Form1: <pre class="fixed_text">     MaxButton = False MDIChild = True MinButton = False WhatsThisButton = True WhatsThisHelp = True </li> Press the F5 key to run the project. The What's This ('?') button disappears from Form1's title bar.</li></ol>

Additional query words: vb5

Keywords: kbbug KB173638

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