Супер дополнение! Лучше чем TST Focus Preceding Tab On Close, пользовался ним ранее. В этом дополнении нет бага с кратким переходом на правую вкладку и только потом на левую, сразу переходит куда нужно. + отличная идея - сначала переходить на предыдущую вкладку потом на левую и когда закончились на правую. Огромная благодарность автору, удачи Вам!

This addon did exactly what I expected! thank you!
非常感謝!這套件太神了!

非常好的扩展，但是稍有不足，是否能有如下操作：
1 当前浏览器标签页A
2 点击标签页A里的任何链接a1，a2，a3....并且是按顺序紧靠A右边后台打开，此时A（前台），a1.a2.a3都是后台未读状态（子标签页）。
3 切换至a1（前台）点击里面任何相同或不同域名的链接aa1前台打开浏览（孙标签页或其他网站），此时a2.a3仍旧是后台未读状态。
4 浏览完aa1（孙标签页或其他网站）后关闭该标签页或其他网站后自动切换至a1（子标签页），此时a2.a3仍旧是后台未读状态。
5 关闭a1（子标签页）后自动切换至a2（子标签页），此时a3仍旧是后台未读状态。
6 如上类似操作浏览完全部a2，a3，a4...关闭后自动切换至父标签页A。
上述的操作只有旧版的tab_utilities_fixed能够做到(1 关闭选取未读亲属标签页，2 上次选取的标签页）。希望能更加完善。谢谢！

Great addon!
Bug: when I try (using address bar) to select the tab that is already opened (by entering url or name of opened tab to the address bar), I'm switched to the last selected tab instead of switching to the tab that I've selected in the address bar.

steps:
1. open any site
2. in separate tab open another site
3. switch to the tab from step 2
4. create new tab and start typing (in address bar) url or name of the tab from step 1
5. select tab from step 1 in the list of suggestions (in address bar) and click on it or press enter

actual result: I'm switched to the tab from step 2
expected result: I should be switched to the tab from step 1 (as I've selected it in the address bar)

Choosing Last accessed tab and Skip hidden works great most of the time. It goes back to the previous active tab without reloading it. Seems like this should be the default Firefox behavior, but isn't for some reason. Skip hidden is needed with the Simple Tab Groups add-on to avoid switching tab groups unexpectedly.
Bug: In FF 65, select Left tab doesn't work if the browser has just been started. It always defaults to the right tab.

firefox 65，直接激活左侧标签，而不是先激活右侧标签再切换，类似插件中，目前唯一一个关闭标签不闪烁的。

Works as expected, but...: Configured to activate left tab. After closing tab it shows for a moment another tab before activating left tab. Very unpleasant and tires the eyes. If add-on is disabled then activating relevant tab after closing a tab works nice and without such glitches.

This add-on does exactly what I was looking for.

Kind of shame on Mozilla to have an add-on needed for that, it should be built in and configurable by the user.

The default behavior (activate right tab after closing current) is just nonsense and bothered me much.

I'm glad I've found this, thank you!

I have issue with this addon working together with Simple Tab Groups (by Drive4k).

Occasionaly, when switching between tab groups, last selected tab (I mean current active tab) "moves" to switched group and "stays" there as last tab.

I was unable to reproduce this reliably to find exact cirquimstances.

Disabling either of these two addons of course removes the issue.

=======
Update: I have figured this issue out.

When I switch from group A to group B and then right away close active tab in this B group - I am switched back to A group. That works like it should be: last active tab becomes that one in A group.

But if I switch back to group B again - then any active tab from A "moves" to group B.

Disabling your addon resolves this issue.