This morning Firefox did an update, or something, and it changed the look for the toolbars. It added a new tab, and a plus sign. I made sure that none of the "tab" options were checked in the options, none are. I downloaded an old version, removed the new version, then reloaded with the old. I did this with two older versions. I don't want anything on the top left that has anything to do with tabs. It wasn't there before this morning.