[hnand]

Thanks! I wanted to read comments in a breadth-first manner, and I knew from the start that using Apple navigation solutions wouldn't work for me, the visual change on the screen between two states would be too big and distracting.

I made a few prototypes, experimented with omni-directional scrolling (comments don't change their relative position to each other, but you kind of move the viewfinder and it sticks to the edges of subtrees), color coding in different patterns and nothing felt good. I gave up and a few months later when I was thinking about a different problem, I just had a light-bulb moment about this one, mind works in mysterious ways I guess. It was unnecessary complicated at first (like dragging the designated "borders" with the comment staying fixed in one place), but I simplified it in the process quite a bit.

It looks pretty straightforward now, but I think a lot of people would be surprised to see how many tricks are there for it to actually look and feel that way.