Make State button interaction less confusing

* lisp/cus-edit.el (custom-variable-current-value): New function.
(custom-variable-backup-value): Use it.
(custom-variable-set, custom-variable-mark-to-reset-standard): Check
that old value is different than the new one.  If it is, make a
backup.  This way, we avoid offering the Set to Backup Value
unnecesarily.
(custom-variable-reset-saved): Reset the variable-comment property for
the variable, to help custom-variable-state be more correct.  Also
check if we should backup old value.
(custom-variable-state): If a variable was set to the standard value,
say its state is standard rather than set, which is more correct.
Getting the right variable state is important for menu options to be
enabled/disabled, and for displaying the right message to the user
(bug#12864).

diff --git a/lisp/cus-edit.el b/lisp/cus-edit.el
index 510c6e3b4c4045a63789d5e5e1c2f81b6ccf0dc3..85c197b400f8d4763a2e13ced8a57234be6e7479 100644 (file)
--- a/lisp/cus-edit.el
+++ b/lisp/cus-edit.el
@@ -2789,7 +2789,9 @@ Possible return values are `standard', `saved', `set', `themed',
                   (and (equal value (eval (car tmp)))
                        (equal comment temp))
                 (error nil))
-              'set
+               (if (equal value (eval (car (get symbol 'standard-value))))
+                   'standard
+                'set)
             'changed))
          ((progn (setq tmp (get symbol 'theme-value))
                  (setq temp (get symbol 'saved-variable-comment))
@@ -2859,6 +2861,18 @@ otherwise."
 (defun custom-variable-standard-value (widget)
   (get (widget-value widget) 'standard-value))
 
+(defun custom-variable-current-value (widget)
+  "Return the current value of the variable edited by WIDGET.
+
+WIDGET should be a custom-variable widget."
+  (let* ((symbol (widget-value widget))
+         (get (or (get symbol 'custom-get) 'default-value))
+         (type (custom-variable-type symbol))
+         (conv (widget-convert type)))
+    (if (default-boundp symbol)
+        (funcall get symbol)
+      (widget-get conv :value))))
+
 (defvar custom-variable-menu nil
   "If non-nil, an alist of actions for the `custom-variable' widget.
 
@@ -2989,10 +3003,12 @@ Optional EVENT is the location for the menu."
             (setq comment nil)
             ;; Make the comment invisible by hand if it's empty
             (custom-comment-hide comment-widget))
-          (custom-variable-backup-value widget)
+           (setq val (widget-value child))
+           (unless (equal (eval val) (custom-variable-current-value widget))
+            (custom-variable-backup-value widget))
           (custom-push-theme 'theme-value symbol 'user
-                             'set (custom-quote (widget-value child)))
-          (funcall set symbol (eval (setq val (widget-value child))))
+                              'set (custom-quote val))
+          (funcall set symbol (eval val))
           (put symbol 'customized-value (list val))
           (put symbol 'variable-comment comment)
           (put symbol 'customized-variable-comment comment))
@@ -3001,10 +3017,12 @@ Optional EVENT is the location for the menu."
             (setq comment nil)
             ;; Make the comment invisible by hand if it's empty
             (custom-comment-hide comment-widget))
-          (custom-variable-backup-value widget)
+           (setq val (widget-value child))
+           (unless (equal val (custom-variable-current-value widget))
+            (custom-variable-backup-value widget))
           (custom-push-theme 'theme-value symbol 'user
-                             'set (custom-quote (widget-value child)))
-          (funcall set symbol (setq val (widget-value child)))
+                             'set (custom-quote val))
+          (funcall set symbol val)
           (put symbol 'customized-value (list (custom-quote val)))
           (put symbol 'variable-comment comment)
           (put symbol 'customized-variable-comment comment)))
@@ -3073,17 +3091,23 @@ before this operation becomes the backup value."
   (let* ((symbol (widget-value widget))
         (saved-value (get symbol 'saved-value))
         (comment (get symbol 'saved-variable-comment))
+         (old-value (custom-variable-current-value widget))
          value)
-    (custom-variable-backup-value widget)
     (if (not (or saved-value comment))
-        ;; If there is no saved value, remove the setting.
-        (custom-push-theme 'theme-value symbol 'user 'reset)
+        (progn
+          (setq value (car (get symbol 'standard-value)))
+          ;; If there is no saved value, remove the setting.
+          (custom-push-theme 'theme-value symbol 'user 'reset)
+          ;; And reset this property too.
+          (put symbol 'variable-comment nil))
       (setq value (car-safe saved-value))
       (custom-push-theme 'theme-value symbol 'user 'set value)
       (put symbol 'variable-comment comment))
+    (unless (equal (eval value) old-value)
+      (custom-variable-backup-value widget))
     (ignore-errors
       (funcall (or (get symbol 'custom-set) #'set-default) symbol
-               (eval (or value (car (get symbol 'standard-value))))))
+               (eval value)))
     (put symbol 'customized-value nil)
     (put symbol 'customized-variable-comment nil)
     (widget-put widget :custom-state 'unknown)
@@ -3096,7 +3120,9 @@ If `custom-reset-standard-variables-list' is nil, save, reset and
 redraw the widget immediately."
   (let* ((symbol (widget-value widget)))
     (if (get symbol 'standard-value)
-       (custom-variable-backup-value widget)
+       (unless (equal (custom-variable-current-value widget)
+                       (eval (car (get symbol 'standard-value))))
+          (custom-variable-backup-value widget))
       (user-error "No standard setting known for %S" symbol))
     (put symbol 'variable-comment nil)
     (put symbol 'customized-value nil)
@@ -3133,13 +3159,8 @@ becomes the backup value, so you can get it again."
 (defun custom-variable-backup-value (widget)
   "Back up the current value for WIDGET's variable.
 The backup value is kept in the car of the `backup-value' property."
-  (let* ((symbol (widget-value widget))
-        (get (or (get symbol 'custom-get) 'default-value))
-        (type (custom-variable-type symbol))
-        (conv (widget-convert type))
-        (value (if (default-boundp symbol)
-                   (funcall get symbol)
-                 (widget-get conv :value))))
+  (let ((symbol (widget-value widget))
+       (value (custom-variable-current-value widget)))
     (put symbol 'backup-value (list value))))
 
 (defun custom-variable-reset-backup (widget)