I'm fed up with the specific problem of Firefox allowing addons to open a tab and switch to it. When I do an important task, fill out an administrative form, telecommuting, upload a video on Youtube, capture a whole page, in short any task that needs to stay on the page for a long time, it's not at all time to be switched to an update tab, for example, from an addon who abuses this function without way to disable it! Thanks Firefox for not disabling this feature! Another thing, this addon, useful in the past, does not download any video on important sites like Facebook, Youtube (which obliges to install an unknown software to download a video), ... I uninstalled this addon!