Very useful app, although -1 star for missing features. Please consider adding an icon for the address bar where the user can choose between the settings which are updated with a "Save settings" button or once the current tab is reloaded. So far, the user has to go to the preferences menu, change the settings and restart the browser for them to take effect. You could also add a list for which the user can specify websites where every link is opened in a new tab while non-listed websites act on the initial Firefox setting.