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Free keybinding with Tridactyl in Firefox, and in-Emacs editing

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Benjamin Slade

Since the effective demise of the Conkeror web browser, I’ve mainly been using Firefox (with some experimentation with Nyxt browser). I’ve missed the ability to quickly browse with the keyboard and customise keybindings.

I’ve played with the Tridactyl extension for a few years, but Firefox limitations in part have kept me from using it more extensively. But I stumbled across a relatively easy way of “unreserving” reserved Firefox keys (like <C-p>, <C-f> etc.) via an offhand comment at Lobste.rs, which points to a 2 line bit of code to remove reserved keybindings. I repeat it here:

#!/usr/bin/env sh

sudo perl -i -pne 's/reserved="true"/               /g' /usr/lib/firefox/browser/omni.ja
find ~/.cache/mozilla/firefox -type d -name startupCache | xargs rm -rf

This now frees up any key as a potential target for Tridactyl bindings. It’s still not perfect: the ability to remap keys in StumpWM is still easier, but it gives me a better possibility for customisation on machines not running StumpWM.

One thing I’ve added to all machines is a better way of dealing with Tridactyl’s function to edit browser text areas in an external browser (bound to C-i by default). In Tridactyl I run in the command area :set editorcmd emacsclient -c %f. This opens up an Emacs frame connected to the default daemon. However, I wanted a quick way of “entering”/“saving” the text and closing the frame. An ad-hoc major mode seemed like an easy way, allowing for save and close-frame with C-c C-c:

;; tridactyl mode
(define-derived-mode tridactyl-mode text-mode "tridactyl"
  "A major mode to edit tridactyl-spawned 'editor' text.")
(define-key tridactyl-mode-map (kbd "C-c C-c")
  '(lambda ()
     "save and exit quickly"
     (interactive)
     (save-buffer)
     (clipboard-kill-ring-save (point-min) (point-max)) ; just in case
     (sleep-for 1)
     (delete-frame)))
(provide 'tridactyl-mode)

However, the editorcmd interface seems to have problems running -e '(func)' type calls (maybe there’s a way to get it to work, but it wasn’t obvious to me), so I additionally added an auto-mode-alist regexp to auto-detect tridactyl temporary files:

(add-to-list 'auto-mode-alist '("/tmp/tmp.*\\.txt$" . tridactyl-mode))

And this seems to work well. I still can’t quite get in-Firefox text editing to have Emacs-style bindings, but for anything non-trivial, I can just edit it in Emacs directly in this way.

(Addendum: though I note that at least a number of text boxes seem to require some additional input afterwards to “fix” the editorcmd text; otherwise they revert back to their previous state. A bit irritating. I’ve added a save-to-clipboard bit in the function above as a safety precaution against lost text.)