This is very minor, but it stumped me for a minute; if you select the last tab in a set, it is obviously not joined with the next tab, because it is the last one. So, now right-click, select JOIN NEXT, and it will join the next tab. So it works fine. However, it doesn't not immediately change its own status background colour, so if you're not paying full attention, it looks like clicking it failed.
This is very minor, but it stumped me for a minute; if you select the last tab in a set, it is obviously not joined with the next tab, because it is the last one. So, now right-click, select JOIN NEXT, and it will join the next tab. So it works fine. However, it doesn't not immediately change its own status background colour, so if you're not paying full attention, it looks like clicking it failed.