Jonathan de Boyne Pollard wrote in a message to Richard Stack:

 JdBP>   If you consider that HWND is a "magic cookie", and that 
 JdBP> somewhere in the bowels of Presentation Manager there is a 
 JdBP> structure that represents a window on screen, recording its 
 JdBP> position and whatnot, then window words can simply be 
 JdBP> considered to be elements of this internal structure that are 
 JdBP> available for application use.

This question, I think, is motivated by experience with Windows.  Under
16-bit Windows, "handles" usually represent real values of some
kind, even though they are officially supposed to be treated as magic
cookies.  Insofar as Windows handles are real values, they are usually
either selectors or are indices into internal tables.  Many Windows
programmers rely on these facts, since many of the official Windows
procedures to do things are ridiculously convoluted (such as
MakeProcInstance).

Under OS/2, handles are almost always magic cookies, and the structures
they represent really are inaccessible from an application due to
protection.  There are occasional exceptions, such as the well-known hack
of using zero for a hab or hmod, but these are very rare.
 
-- Mike


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