Is there any more in-depth explanation anywhere about what alt-up/ down really does? I understand there's some sort of columnar behavior, but when I use it in prose text, it seems to behave in a rather baffling manner to me... I've been looking for an equivalent to the (IMO very useful) ctrl-up/down functionality in Emacs (next paragraph, or, rather, next empty line, basically) and thought perhaps this might work somewhat like that -- and it seems to, if I move to the beginning of the line first. (OK, so the "next paragraph" functionality is a question of its own, I guess; is there something like it?)
And while I'm on the topic of navigation (and things I miss from Emacs ;-) -- if I accidentally press cmd-up or down, I completely lose my current location. Any way of "undoing" something like that? (In Emacs I used alt-x x or something like that, to switch position with the position before the navigation.) It's not always that I remember to set a bookmark before this sort of thing -- mainly because it tends to be accidental :->