(when (eq workgroup1 workgroup2)

      (error "Can't swap a workgroup with itself"))

    (unless (and (memq workgroup1 workgroup-list)

                 (memq workgroup2 workgroup-list))

      (error "Both workgroups aren't present in `wg-workgroup-list'."))

    (setf (wg-workgroup-list) (wg-util-swap workgroup1 workgroup2 workgroup-list)

          (wg-session-modified (wg-current-session)) t)))

(defun wg-cyclic-nth-from-workgroup (workgroup &optional n)

  "Return the workgroup N places from WORKGROUP in `wg-workgroup-list'."

  (wg-cyclic-nth-from-elt workgroup (wg-workgroup-list-or-error) (or n 1)))

;;; buffer association

(defun wg-associate-buffers (workgroup window-or-emacs-window-tree)

  "Associate the buffers visible in window elements of

WINDOW-OR-EMACS-WINDOW-TREE with the given WORKGROUP.

WINDOW-OR-EMACS-WINDOW-TREE must be either a window or a tree of

the form produced by `(car (window-tree))'."

  (wg-aif (windowp window-or-emacs-window-tree)

      (with-current-buffer (window-buffer window-or-emacs-window-tree)

        (setq wg-buffer-workgroup workgroup))

    (dolist (w (cddr window-or-emacs-window-tree))

      (when w (wg-associate-buffers workgroup w)))))

(defun wg-associate-frame-buffers ()

  "Associate the buffers visible in the current frame with the

current workgroup (unless it is currently being deactivated)."

  (wg-awhen (wg-current-workgroup :noerror)

    (unless (member it wg-deactivation-list)

      (wg-associate-buffers it (car (window-tree))))))

(defun wg-associate-all-frame-buffers ()

  "Associate all visible buffers with the current

workgroup (unless it is currently being deactivated)."

  (mapcar 'wg-associate-frame-buffers (frame-list)))

(defun wg-buffer-predicate (buffer)

  "Return t iff the given BUFFER should be considered a candidate

for display by `other-buffer' in the current workgroup."

  (or (not wg-associate-buffers)

      (wg-awhen (wg-current-workgroup :noerror)

        (with-current-buffer buffer

          (eq wg-buffer-workgroup it)))))

(defun wg-after-make-frame (frame)

  (set-frame-parameter frame 'buffer-predicate

                       'wg-buffer-predicate))

;;; mode-line

(defun wg-mode-line-buffer-association-indicator (workgroup)

  "Return a string indicating `current-buffer's association-type in WORKGROUP."

  (case (wg-workgroup-bufobj-association-type workgroup (current-buffer))

    (strong wg-mode-line-decor-strongly-associated)

    (weak wg-mode-line-decor-weakly-associated)

    (otherwise wg-mode-line-decor-unassociated)))

(defun wg-mode-line-string ()

  "Return the string to be displayed in the mode-line."

  (let ((wg (wg-current-workgroup t))

        (wg-use-faces wg-mode-line-use-faces))

    (cond (wg (wg-fontify " "

                ;;(consp (cons :div wg-mode-line-decor-left-brace))

                ;;(keywordp (car (cons :div wg-mode-line-decor-left-brace)))

                ;;(:div wg-mode-line-decor-left-brace)

                wg-mode-line-decor-left-brace

                (wg-workgroup-name wg)

                (if (not wg-mode-line-only-name)

                    (progn

                      wg-mode-line-decor-divider

                      (wg-mode-line-buffer-association-indicator wg)

                      wg-mode-line-decor-divider

                      (if (window-dedicated-p)

                                 wg-mode-line-decor-window-dedicated

                               wg-mode-line-decor-window-undedicated)

                      wg-mode-line-decor-divider

                      (if (wg-session-modified (wg-current-session))

                                 wg-mode-line-decor-session-modified

                               wg-mode-line-decor-session-unmodified)

                      (if (wg-workgroup-modified wg)

                          wg-mode-line-decor-workgroup-modified

                        wg-mode-line-decor-workgroup-unmodified)))

                wg-mode-line-decor-right-brace))

          (t (if wg-display-nowg

                 (progn

                   (wg-fontify " "

                     wg-mode-line-decor-left-brace

                     wg-nowg-string

                     wg-mode-line-decor-right-brace))

               "")))))

(defun wg-add-mode-line-display ()

  "Add Workgroups' mode-line format to `mode-line-format'."

    (let ((format '(wg-mode-line-display-on (:eval (wg-mode-line-string))))

      (set-default 'mode-line-format

                   (wg-insert-after format mode-line-format pos))

      (force-mode-line-update))))

(defun wg-remove-mode-line-display ()

  "Remove Workgroups' mode-line format from `mode-line-format'."

  (wg-awhen (assq 'wg-mode-line-display-on mode-line-format)

    (set-default 'mode-line-format (remove it mode-line-format))

    (force-mode-line-update)))

;;; messaging

(defun wg-message (format-string &rest args)

  "Call `message' with FORMAT-STRING and ARGS.

Also save the msg to `wg-last-message'."

  (setq wg-last-message (apply #'message format-string args)))

(defmacro wg-fontified-message (&rest format)

  "`wg-fontify' FORMAT and call `wg-message' on it."

  (declare (indent defun))

  `(wg-message (wg-fontify ,@format)))

;;; fancy displays

;; FIXME: add `wg-display-max-lines' to chop long display strings at max-line

;; and element-name boundaries

(defun wg-element-display (elt elt-string &optional current-elt-p previous-elt-p)

  "Return display string for ELT."

  (cond ((and current-elt-p (funcall current-elt-p elt))

         (wg-fontify (:cur (concat wg-list-display-decor-current-left

                                   elt-string

                                   wg-list-display-decor-current-right))))

        ((and previous-elt-p (funcall previous-elt-p elt))

         (wg-fontify (:prev (concat wg-list-display-decor-previous-left

                                    elt-string

                                    wg-list-display-decor-previous-right))))

        (t (wg-fontify (:other elt-string)))))

(defun wg-workgroup-display (workgroup index)

  "Return display string for WORKGROUP at INDEX."

  (if (not workgroup) wg-nowg-string

    (wg-element-display

     workgroup

     (format "%d: %s" index (wg-workgroup-name workgroup))

     'wg-current-workgroup-p

     'wg-previous-workgroup-p)))

(defun wg-buffer-display (buffer index)

  "Return display string for BUFFER. INDEX is ignored."

  (if (not buffer) "No buffers"

    (wg-element-display

     (wg-get-buffer buffer)

     (format "%s" (wg-buffer-name buffer))

     'wg-current-buffer-p)))

;; (defun wg-display-internal (elt-fn list)

;;   "Return display string built by calling ELT-FN on each element of LIST."

;;   (let ((div (wg-add-face :div wg-list-display-decor-divider))

;;         (i -1))

;;     (wg-fontify

;;       (:brace wg-list-display-decor-left-brace)

;;       (if (not list) (funcall elt-fn nil nil)

;;         (wg-doconcat (elt list div) (funcall elt-fn elt (incf i))))

;;       (:brace wg-list-display-decor-right-brace))))

(defcustom wg-display-max-lines 1

  "FIXME: docstring this"

  :type 'integer

  :group 'workgroups)

(defun wg-display-internal (elt-fn list)

  "Return display string built by calling ELT-FN on each element of LIST."

  (let ((div (wg-add-face :div wg-list-display-decor-divider))

        (wwidth (window-width (minibuffer-window)))

        (i -1)

        (str))

    (setq str

          (wg-fontify

            (:brace wg-list-display-decor-left-brace)

            (if (not list) (funcall elt-fn nil nil)

              (wg-doconcat (elt list div) (funcall elt-fn elt (incf i))))

            (:brace wg-list-display-decor-right-brace)))

    ;; (subseq str 0 wwidth)

    ))

(defun wg-workgroup-list-display (&optional workgroup-list)

  "Return the Workgroups list display string.

The string contains the names of all workgroups in `wg-workgroup-list',

  :type 'boolean

  :group 'workgroups)

(defcustom wg-remap-insert-buffer nil

  "Non-nil means remap `insert-buffer' to `wg-insert-buffer'.

Otherwise, don't remap."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-remap-next-buffer nil

  "Non-nil means remap `next-buffer' to `wg-next-buffer'.

Otherwise, don't remap."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-remap-previous-buffer nil

  "Non-nil means remap `previous-buffer' to `wg-previous-buffer'.

Otherwise, don't remap."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-remap-bury-buffer 'bury

  "Non-nil means remap `bury-buffer'.

`banish' means remap `bury-buffer' to `wg-banish-buffer'.

`bury' or other non-nil means remap `bury-buffer' to

`wg-bury-buffer'.  Otherwise, don't remap."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-ido-entry-buffer-replacement-regexp "^ .*Minibuf.*$"

  "Regexp matching the name of a buffer to replace `ido-entry-buffer'.

The regexp should match the name of a live buffer that will never

be a completion candidate under normal circumstances.  You

probably don't want to change this.  See

`wg-get-sneaky-ido-entry-buffer-replacement'."

  :type 'regexp

  :group 'workgroups)

;; morph customization

(defcustom wg-morph-on nil

  "Non-nil means use `wg-morph' when restoring wconfigs."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-morph-hsteps 9

  "Columns/iteration to step window edges during `wg-morph'.

Values lower than 1 are invalid."

  :type 'integer

  :group 'workgroups)

(defcustom wg-morph-vsteps 3

  "Rows/iteration to step window edges during `wg-morph'.

Values lower than 1 are invalid."

  :type 'integer

  :group 'workgroups)

(defcustom wg-morph-terminal-hsteps 3

  "Used instead of `wg-morph-hsteps' in terminal frames.

If nil, `wg-morph-hsteps' is used."

  :type 'integer

  :group 'workgroups)

(defcustom wg-morph-terminal-vsteps 1

  "Used instead of `wg-morph-vsteps' in terminal frames.

If nil, `wg-morph-vsteps' is used."

  :type 'integer

  :group 'workgroups)

(defcustom wg-morph-truncate-partial-width-windows t

  "Bound to `truncate-partial-width-windows' during `wg-morph'.

Non-nil, this prevents weird-looking continuation line behavior,

and can speed up morphing a little.  Lines jump back to their

wrapped status when `wg-morph' is complete."

  :type 'boolean

  :group 'workgroups)

;; mode-line customization

(defcustom wg-mode-line-display-on t

  "Toggles Workgroups' mode-line display."

  :type 'boolean

  :group 'workgroups

  :set (lambda (sym val)

         (custom-set-default sym val)

         (force-mode-line-update)))

(defcustom wg-mode-line-use-faces nil

  "Non-nil means use faces in the mode-line display.

It can be tricky to choose faces that are visible in both active

and inactive mode-lines, so this feature defaults to off."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-mode-line-only-name t

  "Display only workgroup name in modeline without any flags."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-mode-line-decor-left-brace "("

  "String displayed at the left of the mode-line display."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-right-brace ")"

  "String displayed at the right of the mode-line display."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-divider ":"

  "String displayed between elements of the mode-line display."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-strongly-associated

  #("@" 0 1 (help-echo "This buffer is strongly associated with the \

current workgroup"))

  "Indicates that a buffer is strongly associated with the current workgroup."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-weakly-associated

  #("~" 0 1 (help-echo "This buffer is weakly associated with the \

current workgroup"))

  "Indicates that a buffer is weakly associated with the current workgroup."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-unassociated

  #("-" 0 1 (help-echo "This buffer is unassociated with the \

current workgroup"))

  "Indicates that a buffer is unassociated with the current workgroup."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-window-dedicated

  #("#" 0 1 (help-echo "This window is dedicated to its buffer."))

  "Indicates that the window is dedicated to its buffer."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-window-undedicated

  #("-" 0 1 (help-echo "This window is not dedicated to its buffer."))

  "Indicates that the window is not dedicated to its buffer."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-session-modified

  #("*" 0 1 (help-echo "The session is modified"))

  "Indicates that the session is modified."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-session-unmodified

  #("-" 0 1 (help-echo "The session is unmodified"))

  "Indicates that the session is unmodified."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-workgroup-modified

  #("*" 0 1 (help-echo "The current workgroup is modified"))

  "Indicates that the current workgroup is modified."

  :type 'string

  :group 'workgroups)

(defcustom wg-mode-line-decor-workgroup-unmodified

  #("-" 0 1 (help-echo "The current workgroup is unmodified"))

  "Indicates that the current workgroup is unmodified."

  :type 'string

  :group 'workgroups)

;; display customization

(defcustom wg-use-faces t

  "Non-nil means use faces in various displays."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-time-format "%H:%M:%S %A, %B %d %Y"

  "Format string for time display.  Passed to `format-time-string'."

  :type 'string

  :group 'workgroups)

(defcustom wg-display-battery t

  "Non-nil means include `battery', when available, in the time display."

  :type 'boolean

  :group 'workgroups)

(defcustom wg-list-display-decor-left-brace "( "