Log File Viewer Web App: Auto Scroll Options

I have a small web app to view log files on remote servers. One feature is to emulate the UNIX command "tail --follow", where the display updates each time the log file is appended.

Initially, I had a checkbox labeled "Auto Scroll?", but I want to add a third state: only-at-bottom-edge. (If the log text is scrolled to the bottom of the view-port, then auto scroll.)

The source of my idea was the program output console from JetBrains' IntelliJ Java IDE. There is a nice, hidden feature that enables auto-scroll, but only if scrolled to bottom of the console. (To be clear: I am sure I want three auto scroll options for my web app.)

To add this new, third option, I switched from an HTML checkbox to an HTML select with three choices:

  • Always
  • Only at Bottom Edge
  • Never

What is a better way to name this new, third option?
(As evidenced by the length of this "question", I struggle to name & explain this option succinctly!)

Writing this question made me realise that I can also add mouse-over tooltip to explain this option. If you think it a good idea, then it would be nice if answers could also suggest tooltip text.

Finally, the web app users are highly technical developers and fluent in English.