The framework calls this member function when the size, position, or Z-order is about to change as a result of a call to the SetWindowPos member function or another window-management function.
An application can prevent changes to the window by setting or clearing the appropriate bits in the flags member of the WINDOWPOS structure.
For a window with the WS_OVERLAPPED or WS_THICKFRAME style, the default implementation sends a WM_GETMINMAXINFO message to the window. This is done to validate the new size and position of the window and to enforce the CS_BYTEALIGNCLIENT and CS_BYTEALIGN client styles. An application can override this functionality by not calling its base class.
This member function is called by the framework to allow your application to handle a Windows message. The parameters passed to your function reflect the parameters received by the framework when the message was received. If you call the base-class implementation of this function, that implementation will use the parameters originally passed with the message and not the parameters you supply to the function.