This must be the first PM call issued by any application thread using Presentation Manager facilities.

It returns hab, which is NULL if the initialization is not successful.

The operating system does not generally use the information supplied by the hab parameter to its calls; instead, it deduces it from the identity of the thread that is making the call. Thus an OS/2 application is not required to supply any particular value as the hab parameter. However, in order to be portable to other environments, an application must provide the hab, that is returned by the WinInitialize function of the thread, to any OS/2 function that requires it.

flOptions determines the initial state of message processing with respect to a created window.