Microsoft KB Archive/263922

= Message Sent to a Window Is Not Displayed Properly with Global Hooks Running =

PSS ID Number: 263922

Article Last Modified on 10/16/2002

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The information in this article applies to:


 * Microsoft Windows NT Server 4.0

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This article was previously published under Q263922



SYMPTOMS
When you are running SetWindowsHookEx with WH_CALLWNDPROCRET, messages sent to SendMessage may not display the proper data.



CAUSE
During the initial SendMessage call, the Graphics Device Interface (GDI) processes the message and the buffer that contains the data is then released. Then, when the hook processes the message again, it reinitializes the memory (which contains zeros) and overwrites the program's data buffer with zeros.



RESOLUTION
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix should have the following file attributes or later:   Date        Time    Size       File name   Platform ---  06/26/2000  10:05p  1,251,504  Win32k.sys  Intel 09/21/1999 04:59p    166,160  Gdi32.dll   Intel 09/21/1999 04:59p    166,672  Winsrv.dll  Intel 09/21/1999 04:59p    335,120  User32.dll  Intel



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

Keywords: kbbug kbQFE KB263922

Technology: kbWinNT400search kbWinNTS400 kbWinNTS400search kbWinNTsearch kbWinNTSsearch

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