Large courses can still suffer from scroll of death if they have too many topics.
This means that the user is still having to scroll down quite a bit to reach the topic that they need to get to. This is really important if the topics above have already been completed.
Therefore in the same way that topic titles are not shown in the topic area when not being edited, topics that are 'hidden' should not be displayed - both topic toggle and topic - when not editing. This would allow the user to see only what they needed to see and still allow the course editor to update / adapt the course in editing mode.