pCtlData (PVOID) - input
Pointer to a Control-Data data structure.
The data referenced by this pointer is class-specific data passed to the window procedure by the WM_CREATE message.
This parameter MUST be a pointer rather than a long.
The first 2 bytes in the data referenced by the pointer must be the total size of the data referenced by the pointer (for example see the ENTRYFDATA or the FRAMECDATA structures). PM requires this information to enable it to ensure that the referenced data is accessible to both 16-bit and 32-bit code.