Yes! When attempting to close the last two tabs in the vertical tab list, one after another, the "Tab Closed ↩" popup of whichever tab you close first will arise at the bottom of the list and obstruct the close button ('X') of the remaining tab, for it's full 3 second duration. Hence, to close the last n tabs, you must close the second-to-last tab n - 1 times, and then wait those 3 seconds to close the last tab.