Text Flow uses Freeway’s Action preview functionality to show the Action’s output in Freeway’s design window. This gives you an unprecedented WYSIWYG experience when designing your page.
The preview is based on the last known publish. This is because, currently, the content of the HTML box to which the Action has been applied is only available to Actions during a preview/publish cycle. You also need to have a Site Folder defined as this is necessary for the preview functionality to work.
The Text Flow Action allows you to switch previews on and off - which is helpful when working with the Relative Page Layout Action.