Globally overriding emacs keybindings

Question

Is there a command to globally override a keybinding such that it overrides even the local settings of major modes? global-set-key is overridden by major mode bindings, as stated here: http://www.gnu.org/software/emacs/manual/html_node/emacs/Rebinding.html

Answer 1

No, there is no (built-in) way to set up a key binding that overrides all others. Look at how Emacs searches the keymap by reading "Searching the Active Keymaps".

You could set overriding-terminal-local-map or overriding-local-map to a keymap containing the binding you want, but that'd prevent your buffer from having any buffer/overlay/minor-mode keymaps, pretty much disabling the majority of Emacs.

The next area Emacs looks for a binding is in the character property at the current point - which probably isn't used all over the place, but it's one way your binding would be overridden (unless you muck with character properties to define your key everywhere, really icky).

The next place Emacs looks is in the variable emulation-mode-map-alists, which is probably your best bet. It was set up for packages to use in cases where there are multiple minor-mode keymaps it wants to juggle.

Make a global minor mode (see Defining Minor Modes), put your key binding in there, add your minor mode and keymap into the emulation-mode-map-alists, and turn on your minor mode.

Your key binding will now have precedence over all others, except those earlier in the emulation-mode-map-alist list, or found in character properties, or in the overriding-local-map...

I believe that's the best you can do, w/out hacking Emacs source.