Okay,
Here is a slightly updated version:
literatureandlatte.com/dlbet … notes2.zip
The only difference is that if you place a colon anywhere in an annotation, when it fades out, everything up to the colon won’t get faded out. Obviously in Scrivener you would be able to choose via preference what the label delimiter is (e.g. you might want it to be a dash, or two colons or some such).
(Walafrid, please see my earlier post in this thread and the replies about why I’m not implementing unfading on mouseover. 
)
All the best,
Keith