Hi
I have been a user of the Calibre editor from its beginning, but you can always trust me to get bitten...
I was proofreading a book, and inserting a lot of corrections coming from a text page. After about one hundred of them (I had the feeling I had been saving my work from time to time), I just did a bad move and suppressed some words.
Instinctively I hit the back button (à la LibreOffice) and was suddenly pushed back to the opening of the session. All my inserted corrections were gone (about one hour work). Of course, it's written. I am guilty. Yes.
I think many users would be happy to be able to come back one step at a time. If we could choose in the Preferences the behaviour of this tricky back button (between last step OR last session), it would be a small step forward for civilization...