The GUI an extensive amount of plus buttons when working with sequences, which bring up a drop down menu in the middle pane so that you can add activities, which I have been using. As a new user, it took me a minute to figure out how to add an activity to the Do While loop, since I had been leveraging that way to add activities, and there was no plus button.
Please add a (+) button in the middle of the Do While loop where is says “Drop activity here”.