+This is sadly necessary because Emacs 26 is broken in this regard."
+ :type 'integer)
+
+(defcustom mdw-frame-colour-alist
+ '((black . ("#000000" . "#ffffff"))
+ (red . ("#2a0000" . "#ffffff"))
+ (green . ("#002a00" . "#ffffff"))
+ (blue . ("#00002a" . "#ffffff")))
+ "Alist mapping symbol names to (FOREGROUND . BACKGROUND) colour pairs."
+ :type '(alist :key-type symbol :value-type (cons color color)))
+
+(defun mdw-set-frame-colour (colour &optional frame)
+ (interactive "xColour name or (FOREGROUND . BACKGROUND) pair:
+")
+ (when (and colour (symbolp colour))
+ (let ((entry (assq colour mdw-frame-colour-alist)))
+ (unless entry (error "Unknown colour `%s'" colour))
+ (setf colour (cdr entry))))
+ (set-frame-parameter frame 'background-color (car colour))
+ (set-frame-parameter frame 'foreground-color (cdr colour)))
+
+;; Window configuration switching.
+
+(defvar mdw-current-window-configuration nil
+ "The current window configuration register name, or `nil'.")
+
+(defun mdw-switch-window-configuration (register &optional no-save)
+ "Switch make REGISTER be the new current window configuration.
+If a current window configuration register is established, and
+NO-SAVE is nil, then save the current window configuration to
+that register first.
+
+Signal an error if the new register contains something other than
+a window configuration. If the register is unset then save the
+current window configuration to it immediately.
+
+With one or three C-u, or an odd numeric prefix argument, set
+NO-SAVE, so the previous window configuration register is left
+unchanged.
+
+With two or three C-u, or a prefix argument which is an odd
+multiple of 2, just clear the record of the current window
+configuration register, so that the next switch doesn't save the
+prevailing configuration."
+ (interactive
+ (let ((arg current-prefix-arg))
+ (list (if (or (and (consp arg) (= (car arg) 16) (= (car arg) 64))
+ (and (integerp arg) (not (zerop (logand arg 2)))))
+ nil
+ (register-read-with-preview "Switch to window configuration: "))
+ (or (and (consp arg) (= (car arg) 4) (= (car arg) 64))
+ (and (integerp arg) (not (zerop (logand arg 1))))))))
+
+ (let ((previous mdw-current-window-configuration)
+ (current-windows (list (current-window-configuration)
+ (point-marker)))
+ (register-value (and register (get-register register))))
+ (when (and mdw-current-window-configuration (not no-save))
+ (set-register mdw-current-window-configuration current-windows))
+ (cond ((null register)
+ (setq mdw-current-window-configuration nil)
+ (if previous
+ (message "Left window configuration `%c'." previous)
+ (message "Nothing to do!")))
+ ((not (or (null register-value)
+ (and (consp register-value)
+ (window-configuration-p (car register-value))
+ (integer-or-marker-p (cadr register-value))
+ (null (caddr register-value)))))
+ (error "Register `%c' is not a window configuration" register))
+ (t
+ (cond ((null register-value)
+ (set-register register current-windows)
+ (message "Started new window configuration `%c'."
+ register))
+ (t
+ (set-window-configuration (car register-value))
+ (goto-char (cadr register-value))
+ (message "Switched to window configuration `%c'."
+ register)))
+ (setq mdw-current-window-configuration register)))))