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Q64329: INFO: Windows Message-Processing Caveats

Article: Q64329
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1
Operating System(s): 
Keyword(s): kb16bitonly kbSDKPlatform kbWndw kbWndwMsg
Last Modified: 09-JUN-1999

3.00 3.10
WINDOWS
kbprg

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The information in this article applies to:

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

Do not call any function that may cause control to yield to another application
during the processing of any of the following messages:

  WM_ACTIVATE
  WM_ACTIVATEAPP
  WM_CREATE
  WM_INITDIALOG
  WM_NCCREATE

Certain messages are used to notify applications of some change in Windows's
internal status. While processing one of these messages, an application cannot
call any function that may result in control being yielded to another
application. Forbidden functions include message-processing functions such as
MessageBox(), DialogBox(), GetMessage(), and PeekMessage().

Violating this caveat may cause Windows to exhibit strange visual behavior.

Additional query words: 3.00 3.10

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Keywords          : kb16bitonly kbSDKPlatform kbWndw kbWndwMsg 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1
Issue type        : kbinfo

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