Q111652: BUG: Edit Controls and WS_CLIPCHILDREN Function Differently

Article: Q111652
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1
Operating System(s): 
Keyword(s): kb16bitonly kbEditCtrl kbGrpDSUser kbOSWin310bug
Last Modified: 12-NOV-1999

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) 3.1 
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SYMPTOMS
========

Unnecessary painting is done when an edit control window is created with the
WS_CLIPCHILDREN style bit set.

CAUSE
=====

If an edit control window is created with the WS_CLIPCHILDREN style bit set, a
WM_PAINT message will be sent to the parent. In Windows version 3.0, the
rcUpdate is (0,0,0,0), which makes it very easy to ignore this WM_PAINT message.
In Windows version 3.1, the rcUpdate is the size of the child edit control,
which causes extra painting to be done. The WM_PAINT message is not necessary
because the child control itself does the painting, not the parent.

STATUS
======

Microsoft has confirmed this to be a bug in Windows version 3.1.

Additional query words:

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Keywords          : kb16bitonly kbEditCtrl kbGrpDSUser kbOSWin310bug 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1
Issue type        : kbbug

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