I would like to hide only the comments in my code. I've noted that, sometimes, a small horizontal dash appears along the side vertical line which starts from the minus sign generated when a '%%' is typed in the beginning of a section. It is very useful because if you push on the minus sign, all the raws (codes and comments) between the minus sign and the horizontal dash are hidden. Point is that I'm not able to decide where locate the horizontal dash... I did not understand the logic with which, from time to time, the text editor makes it (the horizontal dash) appear.
Is there a way to make the horizontal dash appear in the beginning of a desired raw?
To make me better understand, I've prepared a picture that include some screenshoot that shows what I mean. You find it attached to the present post.