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A message that is sent to all top-level windows when the SystemParametersInfo function changes a system-wide setting or when policy settings have changed.
Applications should send WM_SETTINGCHANGE to all top-level windows when they make changes to system parameters. (This message cannot be sent directly to a window.) To send the WM_SETTINGCHANGE message to all top-level windows, use the SendMessageTimeout function with the hwnd parameter set to HWND_BROADCAST.
A window receives this message through its WindowProc function.
LRESULT CALLBACK WindowProc( HWND hwnd, // handle to window UINT uMsg, // message identifier WPARAM wParam, // system parameter indicator LPARAM lParam // system parameter area (LPCTSTR) );
When the system sends this message as a result of a change in policy settings, this parameter indicates the type of policy that was applied. This value is 1 if computer policy was applied or zero if user policy was applied.
When the system sends this message as a result of a change in locale settings, this parameter is zero.
When an application sends this message, this parameter must be NULL.
This string can be the name of a registry key or the name of a section in the Win.ini file. When the string is a registry name, it typically indicates only the leaf node in the registry, not the full path.
When the system sends this message as a result of a change in policy settings, this parameter points to the string "Policy".
When the system sends this message as a result of a change in locale settings, this parameter points to the string "intl".
To effect a change in the environment variables for the system or the user, broadcast this message with lParam set to the string "Environment".
If you process this message, return zero.
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Notebook exported on Monday, 7 July 2008, 18:56:50 PM Eastern Daylight Time