Comment 7 for bug 1247458

This is intentional, but perhaps questionably so--it doesn't seem readily understood by users. I guess the intent is to serve as a reminder that the session will not be saved (like Chrome's incognito icon (https://www.google.com/help/hc/images/chrome_95464.gif). Maybe we should consider something less intrusive (and which can be clicked/hovered to obtain an explanation)?