As I work in a multibrowser environment, I maintain a set of my own file:// pages including one for my home page, and frequently used links. As I have a dynamic set of vm's the pages change frequently as new VM's are spun up and later destroyed. I would like to have the home page also open automatically when opening a new tab. Unfortunately this isn't supported as shown by https://support.mozilla.org/en-US/questions/1176854 . Unfortunately the suggestion using a load to local storage, isn't sufficient, as there is no longer a single source of information (think ISO-9000) and I don't want to do it separately for each browser. I am trying the Extension new tab override, but it's restricted. Is this restriction going to be present for all Extensions? Seems like this would be needed to be implemented again in the browser. Perhaps having an endorsed directory (like tomcat) for "approved" file resources would be a good security compromise