Does what it says on the tin.

Вопрос с выделением текста в ссылке наконец-то решен. Спасибо! Супер!

Seem work well.
Seem it need around 100ms to start selecting from middle of link. If not it just start dragging the link.

Edit: sometimes, if I click-drag too fast, it both selects a couple of letters in the link and then starts dragging the link. Would be great if this can be fixed.

There are a couple of other add-ons like it but they aren't webextensions.