Hi
I think that this FileAttachment notation is special case.It have used own his appearance.
I have seen table 164 and it told that:
"An appearance dictionary specifying how the annotation shall be presented visually on the page (see 12.5.5, “Appearance Streams”).
Individual annotation handlers may ignore this entry and provide their own appearances."
Do you think that other plugin can not changed his icon except using named icon ?
Thanks