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Q68360: Control Panel Doesn’t Respond to WM_WININICHANGE Messages

Article: Q68360
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.0,3.1
Operating System(s): 
Keyword(s): kb16bitonly
Last Modified: 06-NOV-1999

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
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SUMMARY
=======

The Control Panel application does not respond to WM_WININICHANGE messages under
Windows. Microsoft considered including this functionality; however, it was
decided that, because the Control Panel changes various items in the system
configuration file (WIN.INI), responding to a WM_WININICHANGE message could
cause a conflict. (For example, if another application changes the text color
while the Control Panel has its color dialog displayed, what is the proper
action for the Control Panel?)

To work around this potential problem, the Control Panel reinitializes itself
each time a new dialog box is displayed. However, this initialization does not
involve querying the WIN.INI file with GetProfileString().

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

Windows caches the WIN.INI file. Therefore, if a regular text editor (other than
Notepad) is used to modify the file, the disk file is updated, however, the
cache is not.

When a WM_WININICHANGE message is broadcast to all top-level windows, each
application can check the WIN.INI cache for relevant changes. However,
applications will not look at the WIN.INI file on disk.

One way to update the cache is to exit Windows and restart. Another way to update
the cache is to call WriteProfileString(NULL,NULL,NULL), which forces a flush of
the cache. A subsequent call to GetProfileString() will cause the WIN.INI file
on disk to be read into the cache.

However, the changes will not be reflected by the Control Panel unless the user
exits and re-enters Windows. Reflecting changes to WIN.INI in the Control Panel
without first exiting Windows is under consideration for inclusion in a future
release of Windows.

Additional query words: 3.00 no32bit 3.10

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Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1

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