Acrobat Reader allows to highlight text and then enter comments to the highlighted text into the separate panel on the right of the text. I use this feature a lot, when reviewing papers. It would be very handy for me if the comments in the right panel were somehow marked with the same colour as the highlighting in the text. Such feature would allow me easily navigate between the comments later, when making a summary: e.g. first selecting green comments, then red comments etc.