A private window class is any class registered within an application. An application registers a private class by calling the WinRegisterClass function. A private class cannot be shared with other applications. When an application terminates, the system removes any data associated with the application's private window classes.
An application can register a private class anytime but, typically, does so as part of application initialization. To register a private class during application initialization, the application also must call WinInitialize and, usually, WinCreateMsgQueue before class registration.
An application cannot de-register a private window class; it remains registered and available until the application terminates.
When an application registers a private window class, it must supply the following information: