org-colview: Allow to force global column view

* lisp/org-colview.el (org-columns): Add new argument to force global
  column view.

* doc/org.texi (Using column view): Document change.

doc/org.texi

@@ -5703,14 +5703,15 @@ today.
 @orgcmd{C-c C-x C-c,org-columns}
 @vindex org-columns-default-format
 Turn on column view.  If the cursor is before the first headline in the file,
-column view is turned on for the entire file, using the @code{#+COLUMNS}
-definition.  If the cursor is somewhere inside the outline, this command
-searches the hierarchy, up from point, for a @code{:COLUMNS:} property that
-defines a format.  When one is found, the column view table is established
-for the tree starting at the entry that contains the @code{:COLUMNS:}
-property.  If no such property is found, the format is taken from the
-@code{#+COLUMNS} line or from the variable @code{org-columns-default-format},
-and column view is established for the current entry and its subtree.
+or the function called with the universal prefix argument, column view is
+turned on for the entire file, using the @code{#+COLUMNS} definition.  If the
+cursor is somewhere inside the outline, this command searches the hierarchy,
+up from point, for a @code{:COLUMNS:} property that defines a format.  When
+one is found, the column view table is established for the tree starting at
+the entry that contains the @code{:COLUMNS:} property.  If no such property
+is found, the format is taken from the @code{#+COLUMNS} line or from the
+variable @code{org-columns-default-format}, and column view is established
+for the current entry and its subtree.
 @orgcmd{r,org-columns-redo}
 Recreate the column view, to include recent changes made in the buffer.
 @orgcmd{g,org-columns-redo}

etc/ORG-NEWS

@@ -208,7 +208,11 @@ When defining a "columnview" dynamic block, it is now possible to add
 an :indent parameter, much like the one in the clock table.
 
 On the other hand, stars no longer appear in an ITEM field.
-*** New variable : ~org-agenda-view-columns-initially~
+*** Columns view
+**** ~org-columns~ accepts a prefix argument
+When called with a prefix argument, ~org-columns~ apply to the whole
+buffer unconditionally.
+**** New variable : ~org-agenda-view-columns-initially~
 The variable used to be a ~defvar~, it is now a ~defcustom~.
 *** Preview LaTeX snippets in buffers not visiting files
 *** New option ~org-attach-commit~

lisp/org-colview.el

@@ -701,10 +701,18 @@ Also sets `org-columns-top-level-marker' to the new position."
 	  (t (org-back-to-heading) (point))))))
 
 ;;;###autoload
-(defun org-columns (&optional columns-fmt-string)
-  "Turn on column view on an org-mode file.
+(defun org-columns (&optional global columns-fmt-string)
+  "Turn on column view on an Org mode file.
+
+Column view applies to the whole buffer if point is before the
+first headline.  Otherwise, it applies to the first ancestor
+setting \"COLUMNS\" property.  If there is none, it defaults to
+the current headline.  With a \\[universal-argument] prefix \
+argument, turn on column
+view for the whole buffer unconditionally.
+
 When COLUMNS-FMT-STRING is non-nil, use it as the column format."
-  (interactive)
+  (interactive "P")
   (org-columns-remove-overlays)
   (move-marker org-columns-begin-marker (point))
   (org-columns-goto-top-level)
@@ -715,9 +723,8 @@ When COLUMNS-FMT-STRING is non-nil, use it as the column format."
   (unless org-columns-inhibit-recalculation (org-columns-compute-all))
   (save-excursion
     (save-restriction
-      (narrow-to-region
-       (point)
-       (if (org-at-heading-p) (org-end-of-subtree t t) (point-max)))
+      (when (and (not global) (org-at-heading-p))
+	(narrow-to-region (point) (org-end-of-subtree t t)))
       (when (assoc-string "CLOCKSUM" org-columns-current-fmt-compiled t)
 	(org-clock-sum))
       (when (assoc-string "CLOCKSUM_T" org-columns-current-fmt-compiled t)