Please allow a whitelist of websites too Rated 4 out of 5 stars

It is great that you have added the feature to blacklist a list of websites on which the addon will not act.

I think a whitelist i.e a list of websites on which the addon acts will be good too. The addon will not work on all websites, but will work only on the whitelisted websites.

This will make it much more useful to me and many others, who for example, want to dim only wikipedia, or only google, and so on....

This review is for a previous version of the add-on (1.1.1-signed.1-signed). 

Multiple modes

As of version 1.3 the dimmer add-on operates in one of two modes. You can set it to ignore most sites, then use the right click menu on a web page to add specific domains (eg: wikipedia) to override the operating mode and apply the dimming.