Puts the focus on the next tab to the right when you close a tab (just like pre-Safari 5.1).
Apple released Safari 12 on 2018-09-17, which sadly broke support for unsigned "legacy" extensions, including Right Exit, and I'm sorry to say that I will not be releasing a new version of Right Exit to replace it.
To make a long story short, I was originally able to develop Right Exit for free, sign it for free, and give it away for free. To rewrite it today so that it would be compatible with Safari 12, however, I would need to register as a paid Apple developer. Right Exit has always been a hobby project of mine, so I can't justify the ongoing cost to register as a developer for something I give away for free, nor can I in good conscious accept donations for something that I lack the time to maintain and support on a regular basis.
While we all look for a replacement, there is a way to get Right Exit working again, at least on a temporary basis that will probably work until Safari 13 is released. That said, it's a bit annoying...
You'll need to do those last two steps again every time you relaunch Safari. Like I said: it's a bit annoying, but at least it's something to hold us over while we look for a full replacement.
I know this isn't the answer you were probably looking for, but I'm afraid it's the best I have right now. That said, if you happen to discover a replacement for Right Exit, I'd really appreciate it if you'd . Not only would I use it, I'd love to share that information here so that others can benefit from it as well.
Safari will update Right Exit automatically if you have automatic updates enabled. To see whether you do, go to Safari Preferences, click on the Extension section, then click on Updates near the bottom.
Major thanks to Lasse Rasinen for OpenAtEnd. Right Exit wouldn't exist without OpenAtEnd since most of its code was based on OpenAtEnd. Thanks as well to Dan Moren at Macworld for bringing OpenAtEnd to my attention.
Safari 5.1 introduced a new "feature" when you close a tab: sometimes it will move your focus left to the prior tab, and other times it will move your focus right to the next tab. But which way it goes is anyone's guess. Annoying!
This extension fixes that. With it, whenever you close a tab, it puts the focus on the next tab to the right (just like pre-Safari 5.1). If you pair it up with OpenAtEnd, which makes new tabs open at the far right side of the tab bar, your tab behavior will be identical to how it was before Safari 5.1. Awesome!