Whatever its stores and however it stores it doesn't matter to me: I moved its storage space to my ~/.Private encrypted directory.
Same thing for my browser: I don't use a master password or rely on its encryption because I set it up so it too saves my profile in the ~/.Private directory.
See here for more information. You can essentially secure any data saved by any app with eCryptfs - at least when you're logged out.
Linux-only of course. In Windows... well, Windows.