vim-patch:8.2.1401: cannot jump to the last used tabpage

Problem:    Cannot jump to the last used tabpage.
Solution:   Add g<Tab> and tabpagnr('#'). (Yegappan Lakshmanan, closes vim/vim#6661,
            neovim #11626)
https://github.com/vim/vim/commit/62a232506d06f6d1b3b7271801c907d6294dfe84

Nvim implemented this feature before Vim, but Vim made some useful changes (e.g:
beeping on failure). Port the changes to closer match Vim (also makes porting
future patches easier).

Also note that because CHECK_CMDWIN was added to goto_tabpage_tp, there is no
need to do the extra work with tabpage_index and goto_tabpage inside
goto_tabpage_lastused to fix cmdwin issues any more (#11692).
Note that while goto_tabpage_tp doesn't check for textlock like goto_tabpage
does, it shouldn't matter as it is already checked for earlier.

Add tags for <C-Tab> to tabpage.txt, and refer to <C-Tab> over CTRL-Tab to be
consistent with other docs like the patch.
Remove mention of "previous tabpage" (it can be confused with the tabpage to the
left, e.g: `:tabprevious`).
Similarly, don't rename old_curtab to last_tab in enter_tabpage (it might be
confused with the right-most tabpage, e.g: `:tablast`).

Cherry-pick Test_tabpage change from v8.2.0634.
https://github.com/vim/vim/commit/92b83ccfda7a1d654ccaaf161a9c8a8e01fbcf76

3 files changed, 9 insertions, 9 deletions

diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index ccc02e83b2..9eec23b7b7 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -8103,15 +8103,15 @@ tabpagebuflist([{arg}])					*tabpagebuflist()*
 tabpagenr([{arg}])					*tabpagenr()*
 		The result is a Number, which is the number of the current
 		tab page.  The first tab page has number 1.
+
 		The optional argument {arg} supports the following values:
 			$	the number of the last tab page (the tab page
 				count).
-			#	the number of the last accessed tab page (where
-				|g<Tab>| goes to).  If there is no previous
-				tab page, 0 is returned.
+			#	the number of the last accessed tab page
+				(where |g<Tab>| goes to).  If there is no
+				previous tab page, 0 is returned.
 		The number can be used with the |:tab| command.
 
-
 tabpagewinnr({tabarg} [, {arg}])			*tabpagewinnr()*
 		Like |winnr()| but for tab page {tabarg}.
 		{tabarg} specifies the number of tab page to be used.
diff --git a/runtime/doc/index.txt b/runtime/doc/index.txt
index d02ab1b759..572b4e3f93 100644
--- a/runtime/doc/index.txt
+++ b/runtime/doc/index.txt
@@ -431,6 +431,7 @@ tag		char	      note action in Normal mode	~
 |<C-LeftMouse>|	<C-LeftMouse>	   ":ta" to the keyword at the mouse click
 |<C-Right>|	<C-Right>	1  same as "w"
 |<C-RightMouse>| <C-RightMouse>	   same as "CTRL-T"
+|<C-Tab>|	<C-Tab>		   same as "g<Tab>"
 |<Del>|		["x]<Del>	2  same as "x"
 |N<Del>|	{count}<Del>	   remove the last digit from {count}
 |<Down>|	<Down>		1  same as "j"
@@ -577,7 +578,7 @@ tag		command		   action in Normal mode	~
 				   following the file name.
 |CTRL-W_gt|	CTRL-W g t	   same as `gt`: go to next tab page
 |CTRL-W_gT|	CTRL-W g T	   same as `gT`: go to previous tab page
-|CTRL-W_g<Tab>|	CTRL-W g <Tab>	   same as `g<Tab>` : go to last accessed tab
+|CTRL-W_g<Tab>|	CTRL-W g <Tab>	   same as |g<Tab>|: go to last accessed tab
 				   page
 |CTRL-W_h|	CTRL-W h	   go to Nth left window (stop at first window)
 |CTRL-W_i|	CTRL-W i	   split window and jump to declaration of
diff --git a/runtime/doc/tabpage.txt b/runtime/doc/tabpage.txt
index 78b5101da7..f06a6bcc34 100644
--- a/runtime/doc/tabpage.txt
+++ b/runtime/doc/tabpage.txt
@@ -196,10 +196,6 @@ gt					*i_CTRL-<PageDown>* *i_<C-PageDown>*
 {count}<C-PageDown>
 {count}gt	Go to tab page {count}.  The first tab page has number one.
 
-CTRL-<Tab>					*CTRL-<Tab>*
-CTRL-W g<Tab>					*g<Tab>* *CTRL-W_g<Tab>*
-g<Tab>		Go to previous (last accessed) tab page.
-
 :tabp[revious]				*:tabp* *:tabprevious* *gT* *:tabN*
 :tabN[ext]				*:tabNext* *CTRL-<PageUp>*
 <C-PageUp>			 *<C-PageUp>* *i_CTRL-<PageUp>* *i_<C-PageUp>*
@@ -219,6 +215,9 @@ gT		Go to the previous tab page.  Wraps around from the first one
 							*:tabl* *:tablast*
 :tabl[ast]	Go to the last tab page.
 
+<C-Tab>						*CTRL-<Tab>* *<C-Tab>*
+CTRL-W g<Tab>					*g<Tab>* *CTRL-W_g<Tab>*
+g<Tab>		Go to the last accessed tab page.
 
 Other commands:
 							*:tabs*