Okay - was trying to find a way to reduce clutter in the menus (typically done by removing unused buttons); so I saw an option to edit the menu bar that appeared above my message window. Instead of editing the items in the bar, it closed the controls completely and as far as I can tell permanently. I can't find anything in settings related to this once-upon-a-time feature. And the button I was trying to remove is still there. As to what to call this control - no clue; it is the "filer" row of buttons above messages - and was a control or two to the right of the buttons [Unread] [Starred] [Contact] ... . It was a funny icon, and another funny icon that hinted they allowed editing the items on the bar -- one option was a toggle to hide/unhide the bar, the second option had a few more choices if I recall right, but clicking it hid the entire hide/unhide and second control. How do I get those back without a full system "restore settings to default" which essentially nukes my install. See image for location of now missing controls.