The framework calls this member function when the CWnd object is about to be hidden or shown.
Specifies whether a window is being shown. It is TRUE if the window is being shown; it is FALSE if the window is being hidden.
Specifies the status of the window being shown. It is 0 if the message is sent because of a ShowWindow member function call; otherwise nStatus is one of the following:
SW_PARENTCLOSING Parent window is closing (being made iconic) or a pop-up window is being hidden.
SW_PARENTOPENING Parent window is opening (being displayed) or a pop-up window is being shown.
A window is hidden or shown when the ShowWindow member function is called, when an overlapped window is maximized or restored, or when an overlapped or pop-up window is closed (made iconic) or opened (displayed on the screen). When an overlapped window is closed, all pop-up windows associated with that window are hidden.
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.