Improve documentation of next-error-highlight-no-select (bug#38778)

* doc/emacs/building.texi (Compilation Mode):
Mention next-error-highlight-no-select.

* lisp/simple.el (next-error-highlight): Add reference to
next-error-highlight-no-select.
(next-error-highlight-no-select): Add reference to
next-error-highlight.

2 files changed, 13 insertions, 5 deletions

diff --git a/doc/emacs/building.texi b/doc/emacs/building.texi
index 02f18865f39..e866eea4a29 100644
--- a/doc/emacs/building.texi
+++ b/doc/emacs/building.texi
@@ -214,6 +214,7 @@ Select a buffer to be used by next invocation of @code{next-error} and
 @kindex C-x `
 @findex next-error
 @vindex next-error-highlight
+@vindex next-error-highlight-no-select
   To visit errors sequentially, type @w{@kbd{C-x `}}
 (@code{next-error}), or equivalently @kbd{M-g M-n} or @kbd{M-g n}.
 This command can be invoked from any buffer, not just a Compilation
@@ -258,7 +259,9 @@ to skip any messages.
 
   When Emacs visits the locus of an error message, it momentarily
 highlights the relevant source line.  The duration of this highlight
-is determined by the variable @code{next-error-highlight}.
+is determined by the variable @code{next-error-highlight} for the locus
+in the selected buffer, and @code{next-error-highlight-no-select} for
+the locus in non-selected buffers.
 
 @vindex compilation-context-lines
   If the @file{*compilation*} buffer is shown in a window with a left
diff --git a/lisp/simple.el b/lisp/simple.el
index 0d8072bf5f0..cb04c982220 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -75,14 +75,16 @@ value of 1 means that nothing is amalgamated.")
   :version "22.1")
 
 (defcustom next-error-highlight 0.5
-  "Highlighting of locations in selected source buffers.
+  "Highlighting of locations in the selected buffer.
 If a number, highlight the locus in `next-error' face for the given time
 in seconds, or until the next command is executed.
 If t, highlight the locus until the next command is executed, or until
 some other locus replaces it.
 If nil, don't highlight the locus in the source buffer.
 If `fringe-arrow', indicate the locus by the fringe arrow
-indefinitely until some other locus replaces it."
+indefinitely until some other locus replaces it.
+See `next-error-highlight-no-select' to customize highlighting
+of the locus in non-selected buffers."
   :type '(choice (number :tag "Highlight for specified time")
                  (const :tag "Semipermanent highlighting" t)
                  (const :tag "No highlighting" nil)
@@ -91,12 +93,15 @@ indefinitely until some other locus replaces it."
   :version "22.1")
 
 (defcustom next-error-highlight-no-select 0.5
-  "Highlighting of locations in `next-error-no-select'.
+  "Highlighting of locations in non-selected source buffers.
+Usually non-selected buffers are displayed by `next-error-no-select'.
 If number, highlight the locus in `next-error' face for given time in seconds.
 If t, highlight the locus indefinitely until some other locus replaces it.
 If nil, don't highlight the locus in the source buffer.
 If `fringe-arrow', indicate the locus by the fringe arrow
-indefinitely until some other locus replaces it."
+indefinitely until some other locus replaces it.
+See `next-error-highlight' to customize highlighting of the locus
+in the selected buffer."
   :type '(choice (number :tag "Highlight for specified time")
                  (const :tag "Semipermanent highlighting" t)
                  (const :tag "No highlighting" nil)