If a document has been commented on and is closed, why is there no prompt "do you want to save"?
If a document has highlights, comments and notes to replace text it is clear the document needs to be saved in order to retain those comments. Why then, if you accidentally close this document is there no prompt "do you want to save your changes"? As soon as a document has been commented on/changed, there should be a prompt like this. If there has been no change, no prompt is needed.