[feature request] view parent comment or/and collapse all comments above until parent

I use that feature in Boost for Reddit a lot, where a comment has a triangle-up quick-view button which shows the parent comment in a pop-up box (and that box has another such button asf.). An alternative, less quick but more permanent, would be a button which collapses all comments above the chosen comment so that the parent is visible.

edit: github issue #480