bug#53485: 29.0.50; [PATCH] Implement alternative sub-buffer support in term.el

bug#53485: 29.0.50; [PATCH] Implement alternative sub-buffer support in term.el

[miha--- via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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In M-x term, try:

  $ seq 100
  $ htop
  Press 'q' to exit htop.

(Instead of 'htop', you could also try with 'emacs -q', 'vi' or any
other full-screen TUI program.)

Current behaviour: htop overwrites a portion of output from the 'seq'
command and htop's contents remain visible on the screen after pressing
'q'.

Proposed behaviour (patch attached): avoid overwriting output from the
'seq' command and erase htop's contents after exiting. This is the
default behaviour of xterm, st and most other terminal emulators.

Best regards.


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From 41d2f635612c2ef7e046b8f38bd81d0393a7a730 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miha=20Rihtar=C5=A1i=C4=8D?= <miha@kamnitnik.top>
Date: Sun, 23 Jan 2022 21:13:24 +0100
Subject: [PATCH] Implement alternative sub-buffer support in term.el

* etc/e/eterm-color.ti: Added termcaps for entering and leaving an
alternative sub-buffer.
* lisp/term.el (term-reset-size): Resize correctly in an alternative
sub-buffer is in use.
(term-handle-ansi-escape):
(term-termcap-format): Handle termcaps for entering and leaving an
alternative sub-buffer.
(term-switch-to-alternate-sub-buffer): New (used to be commented out)
function to enter or leave an alternative sub-buffer.
---
 etc/e/eterm-color    | Bin 1296 -> 1318 bytes
 etc/e/eterm-color.ti |   5 +--
 etc/e/eterm-direct   | Bin 1375 -> 1397 bytes
 lisp/term.el         |  80 ++++++++++++++++++++++++-------------------
 4 files changed, 48 insertions(+), 37 deletions(-)

diff --git a/etc/e/eterm-color b/etc/e/eterm-color
index bf44fa0f36de0f6681fa3172db13a83c414aa42a..fadac25ffcb55b3b3f6812e9c80f848e94f3dcc3 100644
GIT binary patch
delta 283
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zk$PO}j7DH3=8Qn=rNkVd>XA)#1!?kP_Gavw9LOBSY+{}<c?Gi?lX=eOQ_OCR0H64e
At^fc4

delta 270
zcmZ3+HGzv;iqV~c9|$uU_f6yupO_Qo{2vIy8Dba`8UFuIW5{MG0Mh^emx9SkhB}58
zFbgCG16@FoKB(vfAU$<rq3GlQMh@|r4D*28#X!8AVGYAZsFJN9=?#p0Hai&(F`Q<&
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r)xb)$87Dh3N{N|3)x*pK(Uu@hUd;B4b(5o+qbBcWR^I%C*@+PVcS)1K

diff --git a/etc/e/eterm-color.ti b/etc/e/eterm-color.ti
index eeb9b0b6e6..84b27aef5d 100644
--- a/etc/e/eterm-color.ti
+++ b/etc/e/eterm-color.ti
@@ -16,6 +16,7 @@ eterm-color|Emacs term.el terminal emulator term-protocol-version 0.96,
 	am,
 	mir,
 	msgr,
+	nrrmc,
 	xenl,
 	bel=^G,
 	blink=\E[5m,
@@ -77,8 +78,8 @@ eterm-color|Emacs term.el terminal emulator term-protocol-version 0.96,
  	smso=\E[7m,
  	u6=\E[%i%d;%dR,
  	u7=\E[6n,
-#	smcup=\E[?47h,
-#	rmcup=\E[?47l,
+	smcup=\E[47h,
+	rmcup=\E[47l,
 #       rs2 may need to be added
 
 eterm-direct|Emacs term.el with direct-color indexing term-protocol-version 0.96,
diff --git a/etc/e/eterm-direct b/etc/e/eterm-direct
index c113c3713693b948ae9d52e75df5d89957fd0c77..f4c16621eb185d7d0de14b56fb2e2b73a57adab8 100644
GIT binary patch
delta 259
zcmcc5^_7cTjwz5ql7XKglkww3?nF)o7?_w{>JrZI|9>n)5<@zW&S5BIC<D^}|5r2A
z1L;<VE`|wUK1d7(rU6A}K}F{P>4gjv8)YPxGOPl!*8}lph8+xhq4EbACLd%}vOdai
zj^R4P1EAnbhEEK?fiw#v%s2?m3*`#{X<<e&MhPfidh$m`Yerchd67{GNa}N{Ga7;A
q%z-><Mh74%%;*Xvy_vlk=S{9;j$$@3&zO9HS&hj&XY(iKTt)x@PJ&SY

delta 260
zcmey$b)Sn{jwz6V9|$uUpHAdXoLE-k{2vIy8Dba`8UFuIW5{MG0Mh^emx9SkhB}58
zFbgCG16@FoKB(vfAU$<rqpbK$hIv5dVjy15u!dnHRC?>gMrG@r42Kv_Gh6`*-DP;j
z@E%D2fJ(zmWMqV}Sb#J;BNrnNl+Qm|ky&{11x5`<K`={zX%F-N|6)*48BS?NHLyx;
kkjTUZ9E>I)2BRfZu?4d|<D|*W%u$mcGb?ZAVaa3!0GjoLTL1t6

diff --git a/lisp/term.el b/lisp/term.el
index 895dfbed6c..e1ace628b2 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -1270,7 +1270,8 @@ term-reset-size
     (when (/= width term-width)
       (save-excursion
         (term--remove-fake-newlines)))
-    (let ((point (point)))
+    (let ((point (point))
+          (home-marker (marker-position term-home-marker)))
       (setq term-height height)
       (setq term-width width)
       (setq term-start-line-column nil)
@@ -1279,11 +1280,20 @@ term-reset-size
       (term--reset-scroll-region)
       ;; `term-set-scroll-region' causes these to be set, we have to
       ;; clear them again since we're changing point (Bug#30544).
+      (term--unwrap-visible-long-lines width)
       (setq term-start-line-column nil)
       (setq term-current-row nil)
       (setq term-current-column nil)
-      (goto-char point))
-    (term--unwrap-visible-long-lines width)))
+      (goto-char point)
+
+      (when (term-using-alternate-sub-buffer)
+        (term-handle-deferred-scroll)
+        ;; When using an alternative sub-buffer, the home marker should
+        ;; not move forward.  Bring it back by deleting text in front of
+        ;; it.
+        (when (> term-home-marker home-marker)
+          (let ((inhibit-read-only t))
+            (delete-region home-marker term-home-marker)))))))
 
 ;; Recursive routine used to check if any string in term-kill-echo-list
 ;; matches part of the buffer before point.
@@ -1611,6 +1621,7 @@ term-termcap-format
   "%s%s:li#%d:co#%d:cl=\\E[H\\E[J:cd=\\E[J:bs:am:xn:cm=\\E[%%i%%d;%%dH\
 :nd=\\E[C:up=\\E[A:ce=\\E[K:ho=\\E[H:pt\
 :al=\\E[L:dl=\\E[M:DL=\\E[%%dM:AL=\\E[%%dL:cs=\\E[%%i%%d;%%dr:sf=^J\
+:NR:te=\\E[47l:ti=\\E[47h\
 :dc=\\E[P:DC=\\E[%%dP:IC=\\E[%%d@:im=\\E[4h:ei=\\E[4l:mi:\
 :mb=\\E[5m:mh=\\E[2m:ZR=\\E[23m:ZH=\\E[3m\
 :so=\\E[7m:se=\\E[m:us=\\E[4m:ue=\\E[m:md=\\E[1m:mr=\\E[7m:me=\\E[m\
@@ -3539,16 +3550,14 @@ term-handle-ansi-escape
    ((eq char ?h)
     (cond ((eq (car params) 4)  ;; (terminfo: smir)
 	   (setq term-insert-mode t))
-	  ;; ((eq (car params) 47) ;; (terminfo: smcup)
-	  ;; (term-switch-to-alternate-sub-buffer t))
-	  ))
+	  ((eq (car params) 47) ;; (terminfo: smcup)
+	   (term-switch-to-alternate-sub-buffer t))))
    ;; \E[?l - DEC Private Mode Reset
    ((eq char ?l)
     (cond ((eq (car params) 4)  ;; (terminfo: rmir)
 	   (setq term-insert-mode nil))
-          ;; ((eq (car params) 47) ;; (terminfo: rmcup)
-	  ;; (term-switch-to-alternate-sub-buffer nil))
-	  ))
+          ((eq (car params) 47) ;; (terminfo: rmcup)
+	   (term-switch-to-alternate-sub-buffer nil))))
 
    ;; Modified to allow ansi coloring -mm
    ;; \E[m - Set/reset modes, set bg/fg
@@ -3595,32 +3604,33 @@ term-set-scroll-region
   (term-move-columns (- (term-current-column)))
   (term-goto 0 0))
 
-;; (defun term-switch-to-alternate-sub-buffer (set)
-;;   ;; If asked to switch to (from) the alternate sub-buffer, and already (not)
-;;   ;; using it, do nothing.  This test is needed for some programs (including
-;;   ;; Emacs) that emit the ti termcap string twice, for unknown reason.
-;;   (term-handle-deferred-scroll)
-;;   (if (eq set (not (term-using-alternate-sub-buffer)))
-;;       (let ((row (term-current-row))
-;; 	    (col (term-horizontal-column)))
-;; 	(cond (set
-;; 	       (goto-char (point-max))
-;; 	       (if (not (eq (preceding-char) ?\n))
-;; 		   (term-insert-char ?\n 1))
-;; 	       (setq term-scroll-with-delete t)
-;; 	       (setq term-saved-home-marker (copy-marker term-home-marker))
-;; 	       (set-marker term-home-marker (point)))
-;; 	      (t
-;; 	       (setq term-scroll-with-delete
-;; 		     (not (and (= term-scroll-start 0)
-;; 			       (= term-scroll-end term-height))))
-;; 	       (set-marker term-home-marker term-saved-home-marker)
-;; 	       (set-marker term-saved-home-marker nil)
-;; 	       (setq term-saved-home-marker nil)
-;; 	       (goto-char term-home-marker)))
-;; 	(setq term-current-column nil)
-;; 	(setq term-current-row 0)
-;; 	(term-goto row col))))
+(defun term-switch-to-alternate-sub-buffer (set)
+  ;; If asked to switch to (from) the alternate sub-buffer, and already (not)
+  ;; using it, do nothing.  This test is needed for some programs (including
+  ;; Emacs) that emit the ti termcap string twice, for unknown reason.
+  (term-handle-deferred-scroll)
+  (when (eq set (not (term-using-alternate-sub-buffer)))
+    (let ((row (term-current-row))
+          (col (term-horizontal-column)))
+      (cond (set
+             (goto-char (point-max))
+             (if (not (eq (preceding-char) ?\n))
+                 (term-insert-char ?\n 1))
+             (setq term-scroll-with-delete t)
+             (setq term-saved-home-marker (copy-marker term-home-marker))
+             (set-marker term-home-marker (point)))
+            (t
+             (setq term-scroll-with-delete
+                   (not (and (= term-scroll-start 0)
+                             (= term-scroll-end (term--last-line)))))
+             (delete-region term-home-marker (point-max))
+             (set-marker term-home-marker term-saved-home-marker)
+             (set-marker term-saved-home-marker nil)
+             (setq term-saved-home-marker nil)
+             (goto-char (point-max))))
+      (setq term-current-column nil)
+      (setq term-current-row nil)
+      (term-goto row col))))
 
 ;; Default value for the symbol term-command-function.
 
-- 
2.34.1


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bug#53485: 29.0.50; [PATCH] Implement alternative sub-buffer support in term.el

[Lars Ingebrigtsen]

miha@kamnitnik.top writes:

> Proposed behaviour (patch attached): avoid overwriting output from the
> 'seq' command and erase htop's contents after exiting. This is the
> default behaviour of xterm, st and most other terminal emulators.

I think that makes sense, but I think it would be good to add a user
option to get the old behaviour back.  (Some people prefer to be able to
see the last htop (etc) display after quitting the application.)

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#53485: 29.0.50; [PATCH] Implement alternative sub-buffer support in term.el

[miha--- via Bug reports for GNU Emacs, the Swiss army knife of text editors]

[-- Attachment #1.1: Type: text/plain, Size: 546 bytes --]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> miha@kamnitnik.top writes:
>
>> Proposed behaviour (patch attached): avoid overwriting output from the
>> 'seq' command and erase htop's contents after exiting. This is the
>> default behaviour of xterm, st and most other terminal emulators.
>
> I think that makes sense, but I think it would be good to add a user
> option to get the old behaviour back.  (Some people prefer to be able to
> see the last htop (etc) display after quitting the application.)

Thanks, good idea, sending revised patch.

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From 884c26d84c8cc615916f7f9270b16ac615868b83 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miha=20Rihtar=C5=A1i=C4=8D?= <miha@kamnitnik.top>
Date: Sun, 23 Jan 2022 21:13:24 +0100
Subject: [PATCH] Implement alternative sub-buffer support in term.el

* etc/e/eterm-color.ti: Added termcaps for entering and leaving an
alternative sub-buffer.
* lisp/term.el (term-reset-size): Resize correctly in an alternative
sub-buffer is in use.
(term-clear-full-screen-programs): New user option.
(term-handle-ansi-escape):
(term-termcap-format): Handle termcaps for entering and leaving an
alternative sub-buffer.
(term-switch-to-alternate-sub-buffer): New (used to be commented out)
function to enter or leave an alternative sub-buffer.
---
 etc/e/eterm-color    | Bin 1296 -> 1318 bytes
 etc/e/eterm-color.ti |   5 ++-
 etc/e/eterm-direct   | Bin 1375 -> 1397 bytes
 lisp/term.el         |  92 +++++++++++++++++++++++++++----------------
 4 files changed, 60 insertions(+), 37 deletions(-)

diff --git a/etc/e/eterm-color b/etc/e/eterm-color
index bf44fa0f36de0f6681fa3172db13a83c414aa42a..fadac25ffcb55b3b3f6812e9c80f848e94f3dcc3 100644
GIT binary patch
delta 283
zcmbQhwTz2fiqV}xl7XKglkwC<?r=^97?_wC?h?-M|9>n)5<@zW&S5BIC<D^}|5r2A
z1L;<VE`|wUK1d7(rU6A}K}F{P>4glF4H;!5mNKjYa@GU!W`-RMd!Y&rGEAPxsAO}L
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zk$PO}j7DH3=8Qn=rNkVd>XA)#1!?kP_Gavw9LOBSY+{}<c?Gi?lX=eOQ_OCR0H64e
At^fc4

delta 270
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zFbgCG16@FoKB(vfAU$<rq3GlQMh@|r4D*28#X!8AVGYAZsFJN9=?#p0Hai&(F`Q<&
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r)xb)$87Dh3N{N|3)x*pK(Uu@hUd;B4b(5o+qbBcWR^I%C*@+PVcS)1K

diff --git a/etc/e/eterm-color.ti b/etc/e/eterm-color.ti
index eeb9b0b6e6..84b27aef5d 100644
--- a/etc/e/eterm-color.ti
+++ b/etc/e/eterm-color.ti
@@ -16,6 +16,7 @@ eterm-color|Emacs term.el terminal emulator term-protocol-version 0.96,
 	am,
 	mir,
 	msgr,
+	nrrmc,
 	xenl,
 	bel=^G,
 	blink=\E[5m,
@@ -77,8 +78,8 @@ eterm-color|Emacs term.el terminal emulator term-protocol-version 0.96,
  	smso=\E[7m,
  	u6=\E[%i%d;%dR,
  	u7=\E[6n,
-#	smcup=\E[?47h,
-#	rmcup=\E[?47l,
+	smcup=\E[47h,
+	rmcup=\E[47l,
 #       rs2 may need to be added
 
 eterm-direct|Emacs term.el with direct-color indexing term-protocol-version 0.96,
diff --git a/etc/e/eterm-direct b/etc/e/eterm-direct
index c113c3713693b948ae9d52e75df5d89957fd0c77..f4c16621eb185d7d0de14b56fb2e2b73a57adab8 100644
GIT binary patch
delta 259
zcmcc5^_7cTjwz5ql7XKglkww3?nF)o7?_w{>JrZI|9>n)5<@zW&S5BIC<D^}|5r2A
z1L;<VE`|wUK1d7(rU6A}K}F{P>4gjv8)YPxGOPl!*8}lph8+xhq4EbACLd%}vOdai
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zFbgCG16@FoKB(vfAU$<rqpbK$hIv5dVjy15u!dnHRC?>gMrG@r42Kv_Gh6`*-DP;j
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kkjTUZ9E>I)2BRfZu?4d|<D|*W%u$mcGb?ZAVaa3!0GjoLTL1t6

diff --git a/lisp/term.el b/lisp/term.el
index 895dfbed6c..0c8763b462 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -523,6 +523,16 @@ term-suppress-hard-newline
 (make-obsolete-variable 'term-suppress-hard-newline nil
                         "27.1")
 
+(defcustom term-clear-full-screen-programs t
+  "Whether to clear contents of full-screen TUI programs after exit.
+If non-nil, output of full-screen TUI programs is cleared after
+exiting them.  Note however that a minority of such programs
+don't send an appropriate escape sequence to the terminal before
+exiting so their output isn't cleared regardless of this option."
+  :version "29.1"
+  :type 'boolean
+  :group 'term)
+
 ;; Where gud-display-frame should put the debugging arrow.  This is
 ;; set by the marker-filter, which scans the debugger's output for
 ;; indications of the current pc.
@@ -1270,7 +1280,8 @@ term-reset-size
     (when (/= width term-width)
       (save-excursion
         (term--remove-fake-newlines)))
-    (let ((point (point)))
+    (let ((point (point))
+          (home-marker (marker-position term-home-marker)))
       (setq term-height height)
       (setq term-width width)
       (setq term-start-line-column nil)
@@ -1279,11 +1290,20 @@ term-reset-size
       (term--reset-scroll-region)
       ;; `term-set-scroll-region' causes these to be set, we have to
       ;; clear them again since we're changing point (Bug#30544).
+      (term--unwrap-visible-long-lines width)
       (setq term-start-line-column nil)
       (setq term-current-row nil)
       (setq term-current-column nil)
-      (goto-char point))
-    (term--unwrap-visible-long-lines width)))
+      (goto-char point)
+
+      (when (term-using-alternate-sub-buffer)
+        (term-handle-deferred-scroll)
+        ;; When using an alternative sub-buffer, the home marker should
+        ;; not move forward.  Bring it back by deleting text in front of
+        ;; it.
+        (when (> term-home-marker home-marker)
+          (let ((inhibit-read-only t))
+            (delete-region home-marker term-home-marker)))))))
 
 ;; Recursive routine used to check if any string in term-kill-echo-list
 ;; matches part of the buffer before point.
@@ -1611,6 +1631,7 @@ term-termcap-format
   "%s%s:li#%d:co#%d:cl=\\E[H\\E[J:cd=\\E[J:bs:am:xn:cm=\\E[%%i%%d;%%dH\
 :nd=\\E[C:up=\\E[A:ce=\\E[K:ho=\\E[H:pt\
 :al=\\E[L:dl=\\E[M:DL=\\E[%%dM:AL=\\E[%%dL:cs=\\E[%%i%%d;%%dr:sf=^J\
+:NR:te=\\E[47l:ti=\\E[47h\
 :dc=\\E[P:DC=\\E[%%dP:IC=\\E[%%d@:im=\\E[4h:ei=\\E[4l:mi:\
 :mb=\\E[5m:mh=\\E[2m:ZR=\\E[23m:ZH=\\E[3m\
 :so=\\E[7m:se=\\E[m:us=\\E[4m:ue=\\E[m:md=\\E[1m:mr=\\E[7m:me=\\E[m\
@@ -3539,16 +3560,14 @@ term-handle-ansi-escape
    ((eq char ?h)
     (cond ((eq (car params) 4)  ;; (terminfo: smir)
 	   (setq term-insert-mode t))
-	  ;; ((eq (car params) 47) ;; (terminfo: smcup)
-	  ;; (term-switch-to-alternate-sub-buffer t))
-	  ))
+	  ((eq (car params) 47) ;; (terminfo: smcup)
+	   (term-switch-to-alternate-sub-buffer t))))
    ;; \E[?l - DEC Private Mode Reset
    ((eq char ?l)
     (cond ((eq (car params) 4)  ;; (terminfo: rmir)
 	   (setq term-insert-mode nil))
-          ;; ((eq (car params) 47) ;; (terminfo: rmcup)
-	  ;; (term-switch-to-alternate-sub-buffer nil))
-	  ))
+          ((eq (car params) 47) ;; (terminfo: rmcup)
+	   (term-switch-to-alternate-sub-buffer nil))))
 
    ;; Modified to allow ansi coloring -mm
    ;; \E[m - Set/reset modes, set bg/fg
@@ -3595,32 +3614,35 @@ term-set-scroll-region
   (term-move-columns (- (term-current-column)))
   (term-goto 0 0))
 
-;; (defun term-switch-to-alternate-sub-buffer (set)
-;;   ;; If asked to switch to (from) the alternate sub-buffer, and already (not)
-;;   ;; using it, do nothing.  This test is needed for some programs (including
-;;   ;; Emacs) that emit the ti termcap string twice, for unknown reason.
-;;   (term-handle-deferred-scroll)
-;;   (if (eq set (not (term-using-alternate-sub-buffer)))
-;;       (let ((row (term-current-row))
-;; 	    (col (term-horizontal-column)))
-;; 	(cond (set
-;; 	       (goto-char (point-max))
-;; 	       (if (not (eq (preceding-char) ?\n))
-;; 		   (term-insert-char ?\n 1))
-;; 	       (setq term-scroll-with-delete t)
-;; 	       (setq term-saved-home-marker (copy-marker term-home-marker))
-;; 	       (set-marker term-home-marker (point)))
-;; 	      (t
-;; 	       (setq term-scroll-with-delete
-;; 		     (not (and (= term-scroll-start 0)
-;; 			       (= term-scroll-end term-height))))
-;; 	       (set-marker term-home-marker term-saved-home-marker)
-;; 	       (set-marker term-saved-home-marker nil)
-;; 	       (setq term-saved-home-marker nil)
-;; 	       (goto-char term-home-marker)))
-;; 	(setq term-current-column nil)
-;; 	(setq term-current-row 0)
-;; 	(term-goto row col))))
+(defun term-switch-to-alternate-sub-buffer (set)
+  ;; If asked to switch to (from) the alternate sub-buffer, and already (not)
+  ;; using it, do nothing.  This test is needed for some programs (including
+  ;; Emacs) that emit the ti termcap string twice, for unknown reason.
+  (term-handle-deferred-scroll)
+  (when (eq set (not (term-using-alternate-sub-buffer)))
+    (cond
+     (set
+      (goto-char (point-max))
+      (if (not (eq (preceding-char) ?\n))
+          (term-insert-char ?\n 1))
+      (setq term-scroll-with-delete t)
+      (setq term-saved-home-marker (copy-marker term-home-marker))
+      (set-marker term-home-marker (point)))
+     (t
+      (setq term-scroll-with-delete
+            (not (and (= term-scroll-start 0)
+                      (= term-scroll-end (term--last-line)))))
+      (goto-char (point-max))
+      (when term-clear-full-screen-programs
+        (delete-region term-home-marker (point))
+        (set-marker term-home-marker term-saved-home-marker))
+      (set-marker term-saved-home-marker nil)
+      (setq term-saved-home-marker nil)))
+
+    (setq term-start-line-column nil)
+    (setq term-current-column nil)
+    (setq term-current-row nil)
+    (term-handle-deferred-scroll)))
 
 ;; Default value for the symbol term-command-function.
 
-- 
2.34.1


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bug#53485: 29.0.50; [PATCH] Implement alternative sub-buffer support in term.el

[Lars Ingebrigtsen]

<miha@kamnitnik.top> writes:

> Thanks, good idea, sending revised patch.

Great; seems to work perfect.  😀  Pushed to Emacs 29.

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   bloggy blog: http://lars.ingebrigtsen.no