chlane
commented
2 years ago I have an example of overflow in a Tablist. To see it, go to http://www.chrislane.info/clarity3demo1/ and look for the "Overflow Tabs" example. The keyboard operation skips over the overflow button. It easiest to try it with the arrow keys to see how it works.
Sometimes not all tabs can be displayed due to space limitations. Often one sees then an implementation that a menu button is implemented at the right edge, with which a list of further tabs can be shown.
The page https://www.w3.org/TR/wai-aria-practices-1.1/#tabpanel could deal with this case and explain how then the keyboard operation and the ARIA marking has to be done. Is the element reached with arrow keys or at the next tab step? Should it be a button with submenu or a tab with context menu? (see https://github.com/w3c/aria/issues/1630#issuecomment-958424281)