This example sets and later removes an OfficeArt shadow-colour option on a comment shape.
with Workbook.Sheets[1].Range['B2', 'B2'].AddComment('Review').Shape dobegin
OfficeArtOptions.LongValue[optShadowColor] := $00112233;
if OfficeArtOptions.IsDefined[optShadowColor] then
OfficeArtOptions.Delete(optShadowColor);
end;