This extension covers the main TabMixPlus feature which I lost in 57+, but works inconsistently.

Opening new tabs to the right side works great, but setting "left tab" or "right tab" doesn't work consistently at all. It's fine if I close a new tab right after opening, but if switching to other tabs and then back, closing will often select the tab to the right.

On a side note, *where is the source code?* The extension page says that this is licensed under the GPL v3, which mandates source code distribution, but I can't find a link to it anywhere.