When a generic application object (that is, window class) does not quite meet the requirements of an application, a developer may choose to use the generic object and modify its behavior, through subclassing, to meet the specific requirements. This may be easily achieved in conjunction with the methods described above, since the handle of the newly created window is either returned directly by the called routine or indirectly by the window itself. This handle can then be used in the WinSubclassWindow() function call.
The subject of subclassing is described in detail in Subclassing a Window, along with examples of both the WinSubclassWindow() function and a subclass window procedure.