Although New Tabs Tools replaces default New Tab on Firefox 57 with a more familiar layout, it doesn't work properly (for my installation, at least: Windows 32bit). I couldn't add new tiles, while the tool keeps on adding websites from navigation history without any prior warning or 'asking for consent' (and there's no option on Configuration tool to set the desired behaviour...). I miss also some kind of 'drag & drop' feature to add tiles / customize the new tab layout, as former versions of Firefox had by default.