I recently saw a question I wanted to answer, so I typed out an answer in the answer box. After I finished writing it, I realized I couldn't post it because I hadn't created an account on that stack yet. I clicked the button to create an account on that stack (and got no warning about navigating away from the page), and when I returned to the question I found about 2/3 of my answer text was deleted from the text box.
Usually I get a warning when navigating away from a page with an unposted answer, so I assumed here when I got no such warning that my answer would be saved for me. So it seems like something is not working right in this system (either I should have gotten a warning when clicking to create an account, or else my answer should have been properly saved).