Sent to a window when the SetWindowLong function is about to change one or more of the window's styles.
A window receives this message through its WindowProc function.
Indicates whether the window's styles or extended window styles are changing. This parameter can be one or more of the following values.
The extended window styles are changing.
The window styles are changing.
A pointer to a STYLESTRUCT structure that contains the proposed new styles for the window. An application can examine the styles and, if necessary, change them.
An application should return zero if it processes this message.
Minimum supported client
|Windows 2000 Professional [desktop apps only]|
Minimum supported server
|Windows 2000 Server [desktop apps only]|
Build date: 2/25/2013