Broken. Setting "current home page" does not work if homepage is a local file. Even though hitting the home button works for local files. So it should be possible to navigate to any homepage on the event.

They support something they call "local file" option, but it is not a local file, instead it is a static copy of the file loaded somewhere into the extension storage. Therefore any changes to the local file are not reflected. E.g. it is not possible to sync/backup such file.

Also URL bar of the new tab is cluttered with homepage URL, so its very cumbersome to use it.

Perhaps it is not fault of the extension itself, and it is just result of infamous FF anti-features regarding extensions they push constantly. But anyway, it does not work as described. Uninstalling.