In my testing, the highlight tool in DocViewer doesn't automatically open the annotation. When you highlight a section of text, it shows an icon that you then need to click on in order to add a comment. The text box does not open automatically. For those of us that use the highlight tool extensively to add comments, that's a lot of unnecessary extra clicks.
The annotations text box automatically opens with the other selection tools (strikeout, area selection, and draw). I would like to see the highlight tool work the same way.