Hi,
The actual Ctrl+9 key shortcut it's ok but you need the two hands. Would be more handly to use Ctrl+q to switch between the last two tabs you are viewing.
For example, I have twenty tabs, in one tab I'm learning german and while reading I don't know the meaning of a word, so I switch with the mouse to the traslator page tab. Later I press Ctrl+9 to switch back to the reading german tab. Now I found another unknown word. Switch again with the mouse to the traslator tab. And everytime the same.
Would be nice to have a handly key shortcut to switch fastly between the last two tabs used.
Cheers 🙂