You can allow everything by default too with HTTPSB (it still will use blocklists and protect you), so that you won't have to enable stuff for a website to work.
The power button is what I call "hard" allow all, i.e. it turns off completely matrix filtering.
The "all" cell (top left corner of the matrix) is a "soft" allow all, i.e. it allows everything except those hostnames and types of request which are not specifically blacklisted.
