Feature request: Switch to previously used tab when clicking on active tab

[allixx]

I propose an optional feature - clicking on active tab switches to previously selected tab (à la Tab flip feature of pre-quantum Tab Tree addon).

It's quite productive feature to have, as it saves time when cycling through a couple of tabs without having to resort to ctrl+tab shortcut.

Naive (but seemingly working) implementation example attached.
tabflip.diff.txt

[eoger]

/me wonders if I should come up with some kind of public JS API so users can augment tab center.

[allixx]

it can be interesting to explore!
unfortunately firefox is not (yet?) flexible enough to completely override tab close logic :(