Document locally disabling globalized minor modes in the lispref

* doc/lispref/modes.texi (Defining Minor Modes):
Mention disabling global minor modes on a per-major-mode basis.

* etc/NEWS: Clarify entry.

doc/lispref/ChangeLog

@@ -1,3 +1,8 @@
+2012-02-01  Glenn Morris  <rgm@gnu.org>
+
+	* modes.texi (Defining Minor Modes):
+	Mention disabling global minor modes on a per-major-mode basis.
+
 2012-01-31  Chong Yidong  <cyd@gnu.org>
 
 	* syntax.texi (Parsing Expressions): Clarify intro (Bug#10657).

doc/lispref/modes.texi

@@ -1521,8 +1521,15 @@ starts, for example by providing a @code{:require} keyword.
 
 Use @code{:group @var{group}} in @var{keyword-args} to specify the
 custom group for the mode variable of the global minor mode.
+
+When you define a globalized minor mode, you should generally also
+define a non-globalized version to toggle the mode on an individual
+buffer basis.  This allows users to disable a globally enabled minor
+mode in a specific major mode if they wish, by deactivating the local
+minor mode in the major mode's hook.
 @end defmac
 
+
 @node Mode Line Format
 @section Mode-Line Format
 @cindex mode line

etc/NEWS

@@ -1290,8 +1290,9 @@ on-the-fly spell checking for comments and strings.
 *** New hook `change-major-mode-after-body-hook', run by
 `run-mode-hooks' just before any other mode hooks.
 
-*** Enabled globalized minor modes can be disabled in specific modes,
-by running (FOO-mode-hook 0) via a mode hook.
+*** Enabled globalized minor modes can be disabled in specific major modes.
+If the global mode is global-FOO-mode, then run (FOO-mode -1) in the
+major mode's hook, where FOO-mode toggles the mode on a per-buffer basis.
 
 +++
 *** `define-minor-mode' accepts a new keyword :variable.