For now, survey presentation is either question by question, or group of question by group of question.
In some case, i should be interesting to have a survey that could mix both types : some questions displayed one by one, and others displayed all together.
One workaround is now to create a group for each individual question, and display questions by group, but it's not very "light" design for surveys.
So the format of presentation for questions should be set-up at group level.
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