I'm using this extension called New Tab Override and just saw that the dev complained a few years back about how it wasn't possible to highlight the url of a newly opened tab and there hasn't
bl4ze@techhub.social to 
@jqubed also, I found another bug with a title that explains the issue way better: "With a custom new-tab URL, opening a new tab focuses the address bar but does not select the text"
@jqubed I really do suck ass at explaining, have the dev of the extension I'm talking about explain it for you: https://bugzilla.mozilla.org/show\_bug.cgi?id=1409675