This extension prevents user to type a password in a page served without "https" protocol: it disables the input of the password and highlights the password box with red.
I wrote it for people worried about security and privacy. It's compatible with TOR Browser.
The source code is very brief and easy to be read... but I cannot ensure that it works with all websites. For testing purpose, you can temporarily disable the extension adding the GET parameter "disableSSLchecker" to the url, for example: http://www.site.xyz/page?disableSSLchecker