patch 9.1.0147: Cannot keep a buffer focused in a window

Problem:  Cannot keep a buffer focused in a window
          (Amit Levy)
Solution: Add the 'winfixbuf' window-local option
          (Colin Kennedy)

fixes:  #6445
closes: #13903

Signed-off-by: Colin Kennedy <colinvfx@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 210bfdc..e38aa81 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1,4 +1,4 @@
-*options.txt*	For Vim version 9.1.  Last change: 2024 Feb 24
+*options.txt*	For Vim version 9.1.  Last change: 2024 Mar 03
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -8021,6 +8021,8 @@
 			"split" when both are present.
 	   uselast	If included, jump to the previously used window when
 			jumping to errors with |quickfix| commands.
+	If a window has 'winfixbuf' enabled, 'switchbuf' is currently not
+	applied to the split window.
 
 						*'synmaxcol'* *'smc'*
 'synmaxcol' 'smc'	number	(default 3000)
@@ -9471,6 +9473,15 @@
 	Note: Do not confuse this with the height of the Vim window, use
 	'lines' for that.
 
+						*'winfixbuf'*
+'winfixbuf' 'wfb'	boolean	(default off)
+			local to window
+	If enabled, the buffer and any window that displays it are paired.
+	For example, attempting to change the buffer with |:edit| will fail.
+	Other commands which change a window's buffer such as |:cnext| will
+	also skip any window with 'winfixbuf' enabled. However if a command
+	has an "!" option, a window can be forced to switch buffers.
+
 			*'winfixheight'* *'wfh'* *'nowinfixheight'* *'nowfh'*
 'winfixheight' 'wfh'	boolean	(default off)
 			local to window  |local-noglobal|