patch 9.1.1425: tabpanel: there are still some problems with the tabpanel

Problem:  tabpanel: there are still some problems with the tabpanel with
          column handling
Solution: fix the problems and refactor Tabpanel feature (Hirohito
          Higashi).

fixes: #17423
fixes: #17332
closes: #17336

Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index a15a20a..8cce98a 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -1,4 +1,4 @@
-*builtin.txt*	For Vim version 9.1.  Last change: 2025 May 28
+*builtin.txt*	For Vim version 9.1.  Last change: 2025 Jun 01
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -4728,10 +4728,9 @@
 					start of the clicked char
 		All numbers are 1-based.
 
-		If not over a window, e.g. when in the command line, then only
-		"screenrow" and "screencol" are valid, the others are zero.
-
-		When on the |tabpanel|, "wincol" value is zero.
+		If not over a window, e.g. when in the command line or within
+		|tabpanel|, then only "screenrow" and "screencol" are valid,
+		the others are zero.
 
 		When on the status line below a window or the vertical
 		separator right of a window, the "line" and "column" values