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Q185626: BUG: PictureBox Cannot be Made Transparent Using SetWindowLong

Article: Q185626
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:5.0
Operating System(s): 
Keyword(s): kbVC500bug kbGrpDSVB kbDSupport
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Control Creation Edition for Windows, version 5.0 
- Microsoft Visual Basic Learning Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
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SYMPTOMS
========

Attempting to use the Windows SetWindowLong API function to set the window style
of a Visual Basic Picturebox to transparent does not work. However, this method
was successful with earlier versions of Visual Basic.

RESOLUTION
==========

There is not a solution that allows the API to work in this manner on the
intrinsic Visual Basic 5.0 PictureBox control. To work around this problem, you
can replace the PictureBox control with a custom or third party control that
offers the same basic functionality as the PictureBox control but does not
exhibit the same SetWindowLong limitation.

With Visual Basic 6.0, you can build a Transparent UserControl that responds to
mouse events. For additional information, click the article number below to view
the article in the Microsoft Knowledge Base:

  Q185882 HOWTO: Use the HitTest Event and HitBehavior Property

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

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

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

1. Create a new Standard EXE project. Form1 is created by default.

2. Add two PictureBox controls, named Picture1 and Picture2, to Form1.

3. Set the BackColor property of Picture1 to red.

4. Position Picture2 so that it partially overlaps the Picture1 control.

5. Place the following code in the code module of Form1:

        Option Explicit
        Const GWL_EXSTYLE = (-20)
        Const WS_EX_TRANSPARENT = &H20&

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

        Private Sub Form_Load()
            Dim result As Long
            Picture2.ZOrder
            result = SetWindowLong(Picture2.hwnd, GWL_EXSTYLE, _
               WS_EX_TRANSPARENT)
        End Sub

6. Run the sample project.

  RESULT: The Picture2 control is not made transparent so Picture1 is not
  completely revealed. In earlier versions of Visual Basic this code allowed
  Picture1 to be completely revealed.

Additional query words: kbSDKWin32 kbAPI kbVBp kbdsd kbDSupport kbVBp500

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Keywords          : kbVC500bug kbGrpDSVB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500Search kbVBA500 kbVB500 kbZNotKeyword3
Version           : WINDOWS:5.0
Issue type        : kbbug

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