A must have add-on! I don't know why this feature + "New tab" in the context menu + "open new tab" to the right of selected tab doesn't exist by default in Firefox! Thank you to the developer!

太赞了. tabMix 不能用后一直在找类似扩展, 本来都已经死心了, 今天无意间找到这个, 太惊喜了.
必须五星好评

The only tab-closing add-on I know that provides options and actually works!

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)

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。

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!

This addon lets you correct one of Firefox's bigger usability problems: the unpredictability of which tab will be selected when you close a tab. It also does so with the minimum necessary permissions, which in an age of spying browser addons is something to appreciate.

Firefox keeps some internal info about which tabs are 'children' of 'parent' tabs, and depending whether you have clicked around in the tab bar or not, may choose to activate some 'peer' of the closing tab rather than one adjacent to the closing tab. But this information is not communicated to the user at all, the tab bar appears to be just a list of tabs! I'm fairly technically literate and I find this behaviour stunningly confusing, I can only imagine how frustrating this must be to less technical users. I'm not even sure that this description of how it works is 100% right, and I've spent some time looking into it!

In my opinion, Firefox's closing order for tabs without parent-child relationships (selecting the tab to the right) is also wrong. When you open a new tab, it is opened on the right. It only makes sense that closing a tab would select the tab to the left, taking you back toward where you began. The fault doesn't lie entirely with Firefox though, this is also Chrome's behaviour, and the Firefox team must feel much pressure to keep their interface consistent with the competition to make switching easy.

But I digress. These are small user interface issues, but minor details like this can have major impact on the user experience. Kudos to the author for making this extension.

The only flaw is that, when configured to select the tab to the left, there is a brief flash where the tab to the right is selected before switching to the tab to the left. I presume that this is due to a limitation of the current extension API, where the extension reacts to the tab closed event after the tab is gone and Firefox has already made its default next tab selection, and that nothing can be done to fix it. Unfortunate, but not a deal breaker!

Users who care about tab opening behaviour are also encouraged to check out an about:config option added in Firefox 60, which positions new tabs to the right of the opening tab (instead of to the right of the current peer tabs, or at the end of the tab strip entirely):

browser.tabs.insertAfterCurrent = true