Or maybe it's just me. But when I look at the bottom of the Firefox Bookmarks Library window (launched by Bookmarks → Show All Bookmarks) …
… the arrows seem to be pointing in the wrong directions.
Doesn't look so wrong when you zoom in on just that part, but given that this is at the very bottom of the window (first screenshot above), it just feels wrong.
This has been your nanocomplaint of the day. You are now free to move about the cabin.