Toggle ido mode on or off.
With ARG, turn ido-mode on if arg is positive, off otherwise.
Turning on ido-mode will remap (via a minor-mode keymap) the default
keybindings for the `find-file' and `switch-to-buffer' families of
commands to the ido versions of these functions.
However, if ARG arg equals 'files, remap only commands for files, or
if it equals 'buffers, remap only commands for buffer switching.
This function also adds a hook to the minibuffer. (fn &optional ARG)
Determines for which functional group (buffer and files) ido behavior
should be enabled. The following values are possible:
- `buffer': Turn only on ido buffer behavior (switching, killing,
- `file': Turn only on ido file behavior (finding, writing, inserting...)
- `both': Turn on ido buffer and file behavior.
- `nil': Turn off any ido switching.
Setting this variable directly does not take effect;
use either M-x customize or the function `ido-mode'.