This is not a feature, it's rather a possible use, i found yesterday.
While reading the manual of a software, i found that the windows help files don't have bookmarkings.
That's very anoying, if you close the help file and later want to continue reading it in the same page, you have to search through the whole tree for the place you stoped reading (if you can find it
).
So, I found I could just take a fast screenshot and later see where I was reading.