Use `with-silent-modifications' instead of `org-unmodified' when it makes sense

* org-macs.el: Add a comment on when to use `org-unmodified'
and when to use `with-silent-modifications'.

* org-colview.el (org-columns-display-here)
(org-columns-remove-overlays, org-columns-quit)
(org-columns-edit-value, org-columns-compute-all)
(org-columns-compute, org-agenda-colview-compute):
* org-clock.el (org-clock-sum):
* org.el (org-refresh-category-properties)
(org-refresh-properties, org-entry-blocked-p)
(org-agenda-prepare-buffers): Use `with-silent-modifications'
instead of `org-unmodified'.

Thanks to Stefan Monnier for reminding me about `with-silent-modifications'!

lisp/org-clock.el

@@ -1700,7 +1700,7 @@ each headline in the time range with point at the headline.  Headlines for
 which HEADLINE-FILTER returns nil are excluded from the clock summation.
 PROPNAME lets you set a custom text property instead of :org-clock-minutes."
   (interactive)
-  (org-unmodified
+  (with-silent-modifications
     (let* ((re (concat "^\\(\\*+\\)[ \t]\\|^[ \t]*"
 		       org-clock-string
 		       "[ \t]*\\(?:\\(\\[.*?\\]\\)-+\\(\\[.*?\\]\\)\\|=>[ \t]+\\([0-9]+\\):\\([0-9]+\\)\\)"))

lisp/org-colview.el

@@ -223,7 +223,7 @@ This is the compiled version of the format.")
       (setq s2 (org-columns-add-ellipses (or modval val) width))
       (setq string (format f s2))
       ;; Create the overlay
-      (org-unmodified
+      (with-silent-modifications
 	(setq ov (org-columns-new-overlay
 		  beg (setq beg (1+ beg)) string (if dateline face1 face)))
 	(overlay-put ov 'keymap org-columns-map)
@@ -332,7 +332,7 @@ for the duration of the command.")
 	(remove-hook 'post-command-hook 'org-columns-hscoll-title 'local))
       (move-marker org-columns-begin-marker nil)
       (move-marker org-columns-top-level-marker nil)
-      (org-unmodified
+      (with-silent-modifications
 	(mapc 'delete-overlay org-columns-overlays)
 	(setq org-columns-overlays nil)
 	(let ((inhibit-read-only t))
@@ -384,7 +384,7 @@ CPHR is the complex heading regexp to use for parsing ITEM."
 (defun org-columns-quit ()
   "Remove the column overlays and in this way exit column editing."
   (interactive)
-  (org-unmodified
+  (with-silent-modifications
     (org-columns-remove-overlays)
     (let ((inhibit-read-only t))
       (remove-text-properties (point-min) (point-max) '(read-only t))))
@@ -488,7 +488,7 @@ Where possible, use the standard interface for changing this line."
 	  (org-agenda-columns)))
        (t
 	(let ((inhibit-read-only t))
-	  (org-unmodified
+	  (with-silent-modifications
 	    (remove-text-properties
 	     (max (point-min) (1- bol)) eol '(read-only t)))
 	  (unwind-protect
@@ -920,7 +920,7 @@ Don't set this, this is meant for dynamic scoping.")
 
 (defun org-columns-compute-all ()
   "Compute all columns that have operators defined."
-  (org-unmodified
+  (with-silent-modifications
     (remove-text-properties (point-min) (point-max) '(org-summaries t)))
   (let ((columns org-columns-current-fmt-compiled)
 	(org-columns-time (time-to-number-of-days (current-time)))
@@ -996,7 +996,7 @@ Don't set this, this is meant for dynamic scoping.")
 	  (if (assoc property sum-alist)
 	      (setcdr (assoc property sum-alist) useval)
 	    (push (cons property useval) sum-alist)
-	    (org-unmodified
+	    (with-silent-modifications
 	      (add-text-properties sumpos (1+ sumpos)
 				   (list 'org-summaries sum-alist))))
 	  (when (and val (not (equal val (if flag str val))))
@@ -1509,9 +1509,8 @@ This will add overlays to the date lines, to show the summary for each day."
 	(save-excursion
 	  (save-restriction
 	    (widen)
-	    (org-unmodified
+	    (with-silent-modifications
-	     (remove-text-properties (point-min) (point-max)
+	      (remove-text-properties (point-min) (point-max) '(org-summaries t)))
-				     '(org-summaries t)))
 	    (goto-char (point-min))
 	    (org-columns-get-format-and-top-level)
 	    (while (setq fm (pop fmt))

lisp/org-macs.el

@@ -117,6 +117,8 @@ Otherwise return nil."
 (def-edebug-spec org-preserve-lc (body))
 
 ;; Copied from bookmark.el
+;; Use `org-unmodified' to ignore real modifications, otherwise
+;; `with-silent-modifications' is enough to ignore cosmetic ones
 (defmacro org-unmodified (&rest body)
   "Run BODY while preserving the buffer's `buffer-modified-p' state."
   (org-with-gensyms (was-modified)

lisp/org.el

@@ -8948,7 +8948,7 @@ call CMD."
 		  ((symbolp org-category) (symbol-name org-category))
 		  (t org-category)))
 	beg end cat pos optionp)
-    (org-unmodified
+    (with-silent-modifications
       (save-excursion
 	(save-restriction
 	  (widen)
@@ -8973,7 +8973,7 @@ DPROP is the drawer property and TPROP is the corresponding text
 property to set."
   (let ((case-fold-search t)
 	(inhibit-read-only t) p)
-    (org-unmodified
+    (with-silent-modifications
       (save-excursion
 	(save-restriction
 	  (widen)
@@ -12159,11 +12159,10 @@ changes because there are unchecked boxes in this entry."
 
 (defun org-entry-blocked-p ()
   "Is the current entry blocked?"
-  (org-unmodified
+  (with-silent-modifications
     (if (org-entry-get nil "NOBLOCKING")
 	nil ;; Never block this entry
-     (not
+      (not (run-hook-with-args-until-failure
-      (run-hook-with-args-until-failure
 	    'org-blocker-hook
 	    (list :type 'todo-state-change
 		  :position (point)
@@ -17601,7 +17600,7 @@ When a buffer is unmodified, it is just killed.  When modified, it is saved
 	      (org-check-agenda-file file)
 	      (set-buffer (org-get-agenda-file-buffer file)))
 	    (widen)
-	    (org-unmodified
+	    (with-silent-modifications
 	      (org-refresh-category-properties)
 	      (org-refresh-properties org-effort-property 'org-effort)
 	      (org-refresh-properties "APPT_WARNTIME" 'org-appt-warntime)