Holy cow, I wrote a book!
Blue means compressed; green means encrypted.
This is an example of one of those "come on, it's a tiny, simple feature" requests.
Yes, the code to do this isn't particularly complicated, but it adds another element
of "Ha ha, I'm going to do something in a way that you will never be able to figure
out unless somebody tells you."
We get a lot of these little requests. If we accepted them all, you'd have icons with
so many incomprehensible decorations you'd never be able to figure out what all the
colors and markers mean.
So the next time you say to yourself, "Windows should change the appearance of X if
simple condition Y," imagine what it would be like if we actually did even twenty
of those simple things.