Nope. They are not shown as if by structure. They are shown by file type. People coming from Sigil assume they are shown by structure because it looks like Sigil's file browser. I am not going to cripple ebook edit just to conform to expectations of ex-Sigil users.
There will be a tool to automatically re-arrange the files in whatever folder structure you like so you can normalize the structure when starting work on a book. Other than that, I really have no interest in adding more UI for managing meaningless inside book folder structures. For the *vast* majority of books putting files in folders is utterly pointless. For the few where it might have a legitimate use, edit book actually allows you to put files in whatever folders make sense *to you*.
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