I don’t know if I’m doing something wrong, or the behavior has changed (haven’t used it in a few weeks/builds), but every line now has hollow circles at the beginning, no matter what theme I’m using.
It is supposed to look like that. They are called “handles”. When there are children, you can click on the handles and the children will collapse changing the color of handle indicating there are some collapsed children there. You can change the color of the handles if you want. Just check the documentation on themes.