This handy feature is something I really missed from my previous editor. The function is pretty straightforward; select a whole word by double-clicking, dragging or with keyboard and it automatically highlights all occurrences of the selected word across the document. Deselecting turns off highlighting.

I used to use this feature all the time selecting some tag or keyword and being able to instantly locate close tags or other word instances in current file.

EDIT: Hmm, I spoke too soon; V11 beta new feature, "auto-markers", works great and is exactly what I wanted and even more; I don't know how I missed that!
Now if only I could find how to not auto-enable FindBar when closing the marker customization dialog. Seems we have a small bug here...

Awesome job, Yutaka! Thanks!