NAME
     GfxLookUp -- find a graphics extended node associated with a 
                     given pointer (V36)

   SYNOPSIS
       result = GfxLookUp( pointer );
       d0                   a0

        struct extendednode *gfxlookup( void *);

   FUNCTION
        Finds a special graphics extended data structure (if any) associated
        with the pointer to a data structure (eg: viewextra associated with
        a view structure).

   INPUTS
        pointer = a pointer to a data structure which may have an
                  extendednode associated with it (typically a view ).

   RESULT
        result = a pointer to the extendednode that has previously been
                 associated with the pointer.

   BUGS

   SEE ALSO
        graphics/gfxnodes.h gfxnew() gfxfree() gfxassociate()