When a page has a header/footer, the user may delete it but can't revert back after deletion. This is annoying when using templates because these header/footer can't be protected. Thus a deletion by mistake, which is really easy using the on-screen menu (even though there's a warning), forces the user to restart from scratch. The solution would be to allow to undo the deletion and/or propose a page header/footer locking option. The second has my preference.
*** This bug has been marked as a duplicate of bug 46561 ***