This feature would let you highlight the important sections of a document in a more flexible way. This feature would highlight the important features in yellow, like many programs do, but with a click of a button it would allow you to remove the non-highlighted text, thus providing you with highlights only. Other times, when you need more than highlights, press a button to hide highlights, so that you could view the document in its original form.
Both of these features would help a person review materials in a more dynamic way without having to make several copies.-- bob, Jun 07 2011random, halfbakery