change osx-command-as default for ⌘ to hyper instead of super

The purpose of this PR is to set the default for ⌘ to `hyper' and to provide the
function `kbd-mac-command` to replace `kbd' when defining keybindings for ⌘ in
case someone decides to explicitly set osx-command-as to `super' or `alt'.

There are problems setting osx-command-as to `alt' and `super',
so we use `hyper' as a default instead because, for example:
  - Using `alt':   Command-x or Command-m inserts, respectively: × µ
  - Using `super': Control-Command-f produces keycode: <C-s-268632078>
Setting to `hyper' seems to avoid both types of the above problems.
Also, while it is possible, it is not recommended to set to `meta'
since standard OSX shortcuts would overshadow important keys such
as M-x.

Two other small changes include:

  - Commenting out the code that defines <C-s-268632078> (C-s-f) since it is
    unnecessary if we use `hyper' as the default; and if we really want to use
    `super' then we should figure out how to solve the weird keycode issue.

  - add keybinding for ⌘` (Command-backtick) to `other-window'.
    Emacs usually swallows this keystroke, so other-window basically restores
    the default behavior that most Mac OSX users would expect.

layers/+os/osx/README.org

@@ -15,7 +15,7 @@
 
 * Description
 Spacemacs is not just emacs+vim. It can have OSX keybindings too! This layer
-globally defines common OSX keybindings. ~⌘~ is set to ~super~ and ~⌥~ is set to
+globally defines common OSX keybindings. ~⌘~ is set to ~hyper~ and ~⌥~ is set to
 ~meta~. Aside from that, there's nothing much, really.
 
 While in =dired= this layer will try to use =gls= instead of =ls=.
@@ -37,7 +37,7 @@ The different modifier keys can be set as follows:
 
 #+BEGIN_SRC emacs-lisp
   (setq-defaults dotspacemacs-configuration-layers '(
-     (osx :variables osx-command-as       'super
+     (osx :variables osx-command-as       'hyper
                      osx-option-as        'meta
                      osx-control-as       'control
                      osx-function-as      'none
@@ -115,6 +115,7 @@ To get =gls= install coreutils homebrew:
 | ~⌘ w~       | Close window                |
 | ~⌘ W~       | Close frame                 |
 | ~⌘ n~       | New frame                   |
+| ~⌘ `~       | Other frame                 |
 | ~⌘ z~       | Undo                        |
 | ~⌘ Z~       | Redo                        |
 | ~⌃ ⌘ f~     | Toggle fullscreen           |

layers/+os/osx/config.el

@@ -16,10 +16,19 @@
    option key to type common characters.
    Default: `deprecated'")
 
-(defvar osx-command-as 'super
+(defvar osx-command-as 'hyper
   "Sets the key binding of the `COMMAND' key on OSX.
    Possible values are `super' `meta' `hyper' `alt' `none'.
-   Default: `super'.")
+   Default: `hyper'.")
+;; There are problems setting osx-command-as to `alt' and `super',
+;; so we use `hyper' as a default instead because, for example:
+;;   - Using `alt':   Command-x or Command-m inserts, respectively: × µ
+;;   - Using `super': Control-Command-f produces keycode: <C-s-268632078>
+;; Setting to `hyper' seems to avoid both types of the above problems.
+;; Also, while it is possible, it is not recommended to set to `meta'
+;; since standard OSX shortcuts would overshadow important keys such
+;; as M-x.
+
 (defvar osx-option-as 'meta
   "Sets the key binding of the `OPTION' key on OSX.
    Possible values are `super' `meta' `hyper' `alt' `none'.

layers/+os/osx/keybindings.el

@@ -15,7 +15,7 @@
   ;; this is only applicable to GUI mode
   (when (display-graphic-p)
 
-    ;; `Command' key is by default bound to SUPER (s-*).
+    ;; `Command' key is by default bound to HYPER (H-*),
     ;; `Option' key is by default bound to META (M-*).
     ;; `Function' key is by default not rebound.
     ;; `Control' key is by default not rebound.
@@ -48,25 +48,39 @@
                (when (member key-value allowed-values)
                  (setf (symbol-value internal-var) key-value))))
 
+    (defun kbd-mac-command (keys)
+      "Wraps `kbd' function with Mac OSX compatible Command-key (⌘).
+KEYS should be a string such as \"f\" which will be turned into values
+such as \"H-f\", \"s-f\", or \"A-f\" depending on the value of
+`mac-commmand-modifier' which could be `hyper', `super', or `alt'.
+KEYS with a string of \"C-f\" are also valid and will be turned into
+values such as \"H-C-f\".
+Returns nil if `mac-command-modifier' is set to `none' or something
+other than the three sane values listed above."
+      (let ((found (assoc mac-command-modifier
+                          '((hyper . "H-")
+                            (super . "s-")
+                            (alt   . "A-")))))
+        (when found (kbd (concat (cdr found) keys)))))
+
     ;; Keybindings
-    (global-set-key (kbd "s-=") 'spacemacs/scale-up-font)
-    (global-set-key (kbd "s--") 'spacemacs/scale-down-font)
-    (global-set-key (kbd "s-0") 'spacemacs/reset-font-size)
-    (global-set-key (kbd "s-q") 'save-buffers-kill-terminal)
-    (global-set-key (kbd "s-v") 'yank)
-    (global-set-key (kbd "s-c") 'evil-yank)
-    (global-set-key (kbd "s-a") 'mark-whole-buffer)
-    (global-set-key (kbd "s-x") 'kill-region)
-    (global-set-key (kbd "s-w") 'delete-window)
-    (global-set-key (kbd "s-W") 'delete-frame)
-    (global-set-key (kbd "s-n") 'make-frame)
-    (global-set-key (kbd "s-z") 'undo-tree-undo)
-    (global-set-key (kbd "s-s")
+    (global-set-key (kbd-mac-command "=") 'spacemacs/scale-up-font)
+    (global-set-key (kbd-mac-command "-") 'spacemacs/scale-down-font)
+    (global-set-key (kbd-mac-command "0") 'spacemacs/reset-font-size)
+    (global-set-key (kbd-mac-command "q") 'save-buffers-kill-terminal)
+    (global-set-key (kbd-mac-command "v") 'yank)
+    (global-set-key (kbd-mac-command "c") 'evil-yank)
+    (global-set-key (kbd-mac-command "a") 'mark-whole-buffer)
+    (global-set-key (kbd-mac-command "x") 'kill-region)
+    (global-set-key (kbd-mac-command "w") 'delete-window)
+    (global-set-key (kbd-mac-command "W") 'delete-frame)
+    (global-set-key (kbd-mac-command "n") 'make-frame)
+    (global-set-key (kbd-mac-command "`") 'other-frame)
+    (global-set-key (kbd-mac-command "z") 'undo-tree-undo)
+    (global-set-key (kbd-mac-command "s")
                     (lambda ()
                       (interactive)
                       (call-interactively (key-binding "\C-x\C-s"))))
-    (global-set-key (kbd "s-Z") 'undo-tree-redo)
-    (global-set-key (kbd "C-s-f") 'spacemacs/toggle-frame-fullscreen)
 
     ;; window manipulation with command key
     (global-set-key (kbd "s-1") 'winum-select-window-1)
@@ -79,5 +93,9 @@
     (global-set-key (kbd "s-8") 'winum-select-window-8)
     (global-set-key (kbd "s-9") 'winum-select-window-9)
 
+    (global-set-key (kbd-mac-command "Z") 'undo-tree-redo)
+    (global-set-key (kbd-mac-command "C-f") 'spacemacs/toggle-frame-fullscreen)
+
     ;; Emacs sometimes registers C-s-f as this weird keycode
-    (global-set-key (kbd "<C-s-268632070>") 'spacemacs/toggle-frame-fullscreen)))
+    ;; (global-set-key (kbd "<C-s-268632070>") 'spacemacs/toggle-frame-fullscreen)
+    ))