Beautifying the Tab Bar

Emacs 27.1 introduced a tab bar and I finally got around to trying it out. I found it particularly useful for switching between a few buffers quickly, particularly because I have muscle memory for the Safari tab keybindings (which I set for Emacs tabs).

I must say, the implementation is really nice. Ultimately customizable (a la everything Emacs). It also has some nice interactions with the mouse (if that’s your jam). You can use drag-and-drop to change tab ordering!

Basic Key Bindings

This was the first thing I setup, especially since I knew exactly what I wanted. These mirror Safari’s tab keybindings.

(global-set-key (kbd "s-{") 'tab-bar-switch-to-prev-tab)
(global-set-key (kbd "s-}") 'tab-bar-switch-to-next-tab)
(global-set-key (kbd "s-t") 'tab-bar-new-tab)
(global-set-key (kbd "s-w") 'tab-bar-close-tab)

The s- prefix key is the “command ⌘” key on a Mac.

I think s-w is set to kill-emacs or delete-frame something similar by default. I personally never want that to happen so I’ve had those functions and keybinding disabled for years now. I also had s-{ and s-} bound to switch between frames (other-frame), but I usually use the Emacs GUI in full screen mode, so using these for tabs makes more sense. At least for right now.

Settings

Of course, the tab bar comes with a bunch of customizable settings. I’m using:

(when (< 26 emacs-major-version)
 (tab-bar-mode 1)                           ;; enable tab bar
 (setq tab-bar-show 1)                      ;; hide bar if <= 1 tabs open
 (setq tab-bar-close-button-show nil)       ;; hide tab close / X button
 (setq tab-bar-new-tab-choice "*dashboard*");; buffer to show in new tabs
 (setq tab-bar-tab-hints t)                 ;; show tab numbers
  (setq tab-bar-format '(tab-bar-format-tabs tab-bar-separator)))
                                            ;; elements to include in bar

The when clause wrapping these settings ensures my configuration is maximally compatible with all modern Emacs versions. I figured out these settings through a combination of looking at the *Customize* menu for Tab Bar and reading the help documentation for each variable.

One setting I really like (but am not using right now), is the ability to have a “Menu” button in the tab bar. This is achieved by adding tab-bar-format-menu-bar at the beginning of the tab-bar-format value list.

Theme

I worked really hard on my modeline and I can reuse all that styling! This is the snippet from my personal dusk theme¹:

;; modeline settings
'(mode-line ((t (:underline nil :overline nil :box (:line-width 8 :color "#353644" :style nil) :foreground "white" :background "#353644"))))
'(mode-line-buffer-id ((t (:weight bold))))
'(mode-line-emphasis ((t (:weight bold))))
'(mode-line-highlight ((((class color) (min-colors 88)) (:box (:line-width 2 :color "grey40" :style released-button))) (t (:inherit (highlight)))))
'(mode-line-inactive ((t (:weight light :underline nil :overline nil :box (:line-width 8 :color "#565063" :style nil) :foreground "white" :background "#565063" :inherit (mode-line)))))
;; tab bar settings
'(tab-bar ((t (:inherit mode-line))))
'(tab-bar-tab ((t (:inherit mode-line :foreground "white"))))
'(tab-bar-tab-inactive ((t (:inherit mode-line-inactive :foreground "black"))))

Binding the Tab Hint Numbers

I have a pretty wonky keybinding setup, where I create my own minor mode key map and use that by default (as recommended by this stackexchange post). Here I use (setq mac-command-modifier 'super).

The tab bar documentation indicates that to enable pressing ⌘-1 (or s-1 as Emacs sees it) to switch to tab number 1 I would need:

(setq tab-bar-select-tab-modifiers "super")

But this didn’t work for me. Instead, I bound each super-number combination (s-1 through s-0) to tab-bar-select-tab and it works!

Final Comments

As I mentioned above, the tab bar implementation is really nice. This reflects the high standards that the Emacs community and developers have, especially for anything that becomes built in. I was able to do all of this implementation and blogging while flying back from a semi-vacation in Greece (where I spent a lot of time improving my blog, if you didn’t notice). An editor with completely built-in documentation and an interface for configuring / customizing is really, really pleasant. Not needing the internet to do something productive feels increasingly rare.

Footnotes

¹ Back when I wrote about package cl being deprecated, I noted that the way I define my theme was outdated. I finally got around to modernizing it, but never wrote about the process. I’m not sure a blog post would be useful, since I’m guessing most readers use existing theme packages. I did start with the customize-create-theme function, which made the process of porting my old color-theme definition to the modern customize format trivial.

You can view my theme in my dotfiles GitHub repo.

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