Migration to new interface
o deal with missing stuff in prop.idl :
   #define STG_E_PROPSETMISMATCHED 0x800300F0

Specification changes to reflect implementation
o threading issues

Unresolved implementation/design issues
o Returing STG_E_INVALIDPOINTER ?
o threading issues -- two ref counts : one for enumerations and one for regular refs
o Enumerating properties of VT_STREAM etc type - do we check that the stream exists ?  Or document
  that just because it is enumerated doesn't mean you can open it ?  How is VT_STREAM enumerated anyway ?
  As a stream or as a string ?

Test cases to consider: