[PATCH] emacs: jump: make multilevel keys do multilevel jump

[David Bremner]

Mark Walters <markwalters1009 at gmail.com> writes:

> notmuch jump allows the user to specify a key sequence rather than
> just a single key for its bindings. However, it doesn't show what has
> already been typed so it can be difficult to see what has
> happened. This makes each key press appear, and the jump menu reduce
> to the possible follow up keys.
> ---
>
> bremner pointed out that multi-key key sequences were unclear in
> tag-jump (and other jump uses). This makes it clearer by displaying
> the keys typed so far and reducing the displayed options based on what
> has been typed so far. Backspace is bound to remove the last typed
> character and return to the previous level. Slightly unfortunately
> emacs likes to call backspace "DEL".

I like the functionality a lot, but some things backspace/DEL caught my
attention

1) It would be nice if k <backspace> aborted the sequence (although it
doesn't claim it will, so technically not a bug)

2) it doesn't seem to work correctly in emacs -nw (I'm testing in emacs
25.1 atm, in case that's relevant). I just get a message
"delete-backward-char: Text is read-only"

There is some information about delete and backspace

      https://www.gnu.org/software/emacs/manual/elisp.html#Function-Keys

The cariable local-function-key map also seems relevant.