The grader can comment in any question type. In the Comments tab, the student's answer is shown as a PDF where the grader can add his annotations. The annotation actions are located at the bottom bar of the page: New comment.
To add comment select "New comment" and choose one of the three different types.
Point - mark a point in the text or on an figure
Area - mark an area in the text or on a figure
Text - just add a comment
The yellow comments box can be positioned everywhere.
To save a comment, simply click outside the yellow comments box and saving is triggered.
To delete a comment, select it, and click Delete selected at the bottom
If you wish to hide comments to focus on the student scripts, click Toggle visibility
A pre-requisite for comments to be shared with students, is that final grading is confirmed.
If the students should receive feedback only, and you do not wish to grade then, grading can be confirmed "empty" without having set any scores or grades