Your comments

I'm using TO on its own now, and have yet to see a tab move around without my help. I'm going to chalk this up to it being "incompatible" with Sidewise, which is... expected.

Sorry for the false alarm.
I will attempt to reproduce this without Sidewise running (once I get all my tabs imported). But I suspect it won't be possible.
Actually, nevermind. I think this is a function of the fact that I'm running Tabs Outliner and Sidewise simultaneously (as I get all my windows organized). I think Sidewise placed the new tab in a particular place, and TO just "followed orders" when it noticed the tab had been moved.

I will also try the Alt-dbl-click "feature". And yes, as it happens, I do have a degree as a programmer, and will take a look at the link you mention.

Also, I'm happy to donate if a product meets my needs. I'm still evaluating whether this does that or not. I *really* like having the much smaller profile that your extension offers. Its much cleaner than Sidewise. I will probably make a suggestion or two once I've gotten past the "new user" phase. Although it is taking me a bit to get used to having to dbl-click to get the effect I want... once I'm past that, I suspect it will be close to perfect.

Thank you for your attention.

Ah, that is a good point. It hadn't occurred to me that it might be Chrome opening the windows, and not not TO. I will try that. And I'm sorry if I got a bit snippy there. I had been at work for 18 hours and was pretty tired. I shouldn't have taken that out on you.