Working directories are directories where files have most
recently been opened. The current directory is inserted at the front
ido-work-directory-list whenever a file is opened with
ido-find-file and other file-related functions.
This user option specifies maximum number of working directories to record.
This user option specifies maximum number of working directories to be
cached. This is the size of the cache of
file-name-all-completions results. Each cache entry is time
stamped with the modification time of the directory. Some systems,
like MS-Windows, have unreliable directory modification times, so you
may choose to disable caching on such systems, or explicitly refresh
the cache contents using the command
(usually C-l) in the minibuffer.