It's a very good improvement to warn the user when a doc is not saved, so the edition is not lost. Now this message is shown:
"This document is not saved. Are you sure that you want to navigate away from it?"
However, for the novice user, they will feel scared when reading it, but they won't know what to do. A reaction could be "Where can I save the document??? How do I save it??? Where is that button? Hurry!" :P
I would provide a more helpful message, with a procedure to follow:
" WARNING: This document is not saved due to a technical problem. Are you sure that you want to navigate away from it?
We advise you to copy the contents you wrote just in case they get lost."
Other solutions are possible, but I feel this too complicated:
"WARNING: This document is not saved. Are you sure that you want to navigate away from it?
We advise you to open another tab in your browser with this document, and check if anything was lost."