Adding Comments
The yellow sticky-pad button 
in the Toolbar is used for adding comments. A comment is a special kind of Action in the Process that is used for documentation and for adding explanatory noted between the actions.
The background color of each comment can be set in different color as a visual clue for differentiating sections of the Process and giving more emphasis to some comments that others.
Neither adding nor deleting Comments has any affect on the behavior of the Process.