59.0.2 (32-bit)
After some time working correctly, just recently I find tabs opening at end of line again.

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It's absurd this isn't the default.

Using Nightly [now 58.0a1 (2017-10-07) (32-bit)] sometimes ctrl_T goes to end-of-tabs instead of the next slot,

Just now, I did ctrl_T from the frst tab, it went to th end of the line; I moved it back manually.
Next I tried it on a mid-tab: fine, it went to next slot.
Tried again on first tab, this time it worked properly.

I suspect it's a photon glitch, some module not loading in time without being checked. Is there a way to ensure it works always?

Additionally, when I ctr_T on the first tab in the visible row, it not only creates a tab, but shifts focus to it (which is an assumption too far), and moves the current tab leftwards out of view. So I then have to move left again to see where I was.

The search function also changes focus to the search page rather than opening it in background. So, if I need to search for several items on a page, I have to go back & forth each time.Could be another piece of slack thinking by mozilla.