I can agree with that, so I have improved it in recent commit.
From now, passwords are by default hidden with "*****", and if you want to show them, you need to click Show passwords button and then agree, that you really want to. It's not ideal though, but to make it really secure, it would be necessary to crypt all passwords with main password.
You can see how it works in action at screenshots:
|Passwords shown as ****|
|You must agree|
|You can see passwords now|