[prawn]

I like how on Reddit you can click to the right of a comment header (username, timestamp, etc) to collapse that subthread. Gives you a much bigger hit target than just [-]. Also saves putting [-] over near the up/down arrows for consistency of positioning, a decision which could otherwise just create trouble on mobile.

[insin]

Ooh, I'm having that feature for the next version of Comments Owl for Hacker News (which already moves the [-] to the left and increases the size of it on mobile), but does that not lead to accidental collapsing while scrolling on mobile?

I've already added using a confirm() for flagging and hiding in list pages on mobile to it because it's so easy to accidentally hit while scrolling.