Different from the old version, now when um split tab's the plugin will open two new browser windows... So now you will have a lot of space in use for nothing, for browser menus, for windows borders and so on... I've just uninstall it and won't use anymore it doesn't help anymore... I use this plugin in environment monitoring displays and was very helpful once I could show many different pages in a single browser windows with view space well used... I've prefer to use the firefox ESR with the old version than this new one...