Optionally avoid that switching to previous or next buffer shows that buffer twice.

* window.el (switch-to-visible-buffer): New option.
(switch-to-prev-buffer, switch-to-next-buffer): Observe
switch-to-visible-buffer.  Make sure that checking for a window
showing a buffer already is done on the same frame.

* windows.texi (Window History): Describe new option
switch-to-visible-buffer.

2 files changed, 20 insertions, 1 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index a326117cdce..494e3416d80 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2012-03-27  Martin Rudalics  <rudalics@gmx.at>
+
+        * windows.texi (Window History): Describe new option
+        switch-to-visible-buffer.
+
 2012-03-27  Glenn Morris  <rgm@gnu.org>
 
         * searching.texi (String Search): Add xref to Emacs manual.
diff --git a/doc/lispref/windows.texi b/doc/lispref/windows.texi
index b541b2419c8..8df32785036 100644
--- a/doc/lispref/windows.texi
+++ b/doc/lispref/windows.texi
@@ -2073,7 +2073,8 @@ or killed or has been already shown by a recent invocation of
 If repeated invocations of this command have already shown all buffers
 previously shown in @var{window}, further invocations will show buffers
 from the buffer list of the frame @var{window} appears on (@pxref{The
-Buffer List}).
+Buffer List}) trying to skip buffers that are already shown in another
+window on that frame.
 @end deffn
 
 @deffn Command switch-to-next-buffer &optional window
@@ -2087,6 +2088,19 @@ can be undone, this function tries to show a buffer from the buffer list
 of the frame @var{window} appears on (@pxref{The Buffer List}).
 @end deffn
 
+By default @code{switch-to-prev-buffer} and @code{switch-to-next-buffer}
+can switch to a buffer that is already shown in another window on the
+same frame.  The following option can be used to override that behavior.
+
+@defopt switch-to-visible-buffer
+If this variable is non-@code{nil}, @code{switch-to-prev-buffer} and
+@code{switch-to-next-buffer} may switch to a buffer that is already
+visible on the same frame, provided the buffer was shown in the argument
+window before.  If it's @code{nil}, @code{switch-to-prev-buffer} and
+@code{switch-to-next-buffer} always try to avoid switching to a buffer
+that is already visible in another window on the same frame.
+@end defopt
+
 
 @node Dedicated Windows
 @section Dedicated Windows