GNU bug report logs - #80091
[PATCH] Update cursor display using Xterm escape sequences

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jared Finder <jared <at> finder.org>
To: Bug-gnu Emacs <bug-gnu-emacs <at> gnu.org>
Subject: [PATCH] Update cursor display using Xterm escape sequences
Date: Sun, 28 Dec 2025 19:14:02 -0800

[Message part 1 (text/plain, inline)]

This patch adds a user option to xterm.el, xterm-set-cursor-type, which 
enables sending xterm escape sequences to update the way the cursor is 
displayed.  Many modern terminals support escape sequences to switch the 
cursor between a filled box, a vertical bar, and a horizontal bar.

I put this behind a user option because instead of capability checking 
because the patch achieves this using post-command-hook.

  -- MJF

[0001-Update-cursor-display-using-Xterm-escape-sequences.patch (text/x-diff, attachment)]

Message #8 received at 80091 <at> debbugs.gnu.org (full text, mbox):

From: Sean Whitton <spwhitton <at> spwhitton.name>
To: 80091 <at> debbugs.gnu.org, Jared Finder <jared <at> finder.org>
Subject: Re: bug#80091: [PATCH] Update cursor display using Xterm escape
 sequences
Date: Mon, 29 Dec 2025 11:43:44 +0000

Hello,

On Sun 28 Dec 2025 at 07:14pm -08, Jared Finder wrote:

> This patch adds a user option to xterm.el, xterm-set-cursor-type, which
> enables sending xterm escape sequences to update the way the cursor is
> displayed.  Many modern terminals support escape sequences to switch the
> cursor between a filled box, a vertical bar, and a horizontal bar.
>
> I put this behind a user option because instead of capability checking because
> the patch achieves this using post-command-hook.

Thanks.  This needs documenting in NEWS and possibly also the manual.

Can you recommend a terminal that supports this on GNU/Linux so I can
test the patch?

-- 
Sean Whitton

Message #11 received at 80091 <at> debbugs.gnu.org (full text, mbox):

From: Jared Finder <jared <at> finder.org>
To: Sean Whitton <spwhitton <at> spwhitton.name>
Cc: 80091 <at> debbugs.gnu.org
Subject: Re: bug#80091: [PATCH] Update cursor display using Xterm escape
 sequences
Date: Mon, 29 Dec 2025 09:37:14 -0800

On 2025-12-29 03:43, Sean Whitton wrote:
> Hello,
> 
> On Sun 28 Dec 2025 at 07:14pm -08, Jared Finder wrote:
> 
>> This patch adds a user option to xterm.el, xterm-set-cursor-type, 
>> which
>> enables sending xterm escape sequences to update the way the cursor is
>> displayed.  Many modern terminals support escape sequences to switch 
>> the
>> cursor between a filled box, a vertical bar, and a horizontal bar.
>> 
>> I put this behind a user option because instead of capability checking 
>> because
>> the patch achieves this using post-command-hook.
> 
> Thanks.  This needs documenting in NEWS and possibly also the manual.

Updated patch attached.

> Can you recommend a terminal that supports this on GNU/Linux so I can
> test the patch?

Try any of the following terminals:

Installable on Debian:
* xfce4-terminal 1.1.4
* gnome-terminal 3.56.2, VTE 0.80.1
* konsole 25.04.2

Terminals on other OSes work too:
* Windows Terminal (on Windows)
* iTerm2 (on MacOS)

As an aside, all of these terminals except Konsole also appear to 
support altering the cursor's color as well.  I've renamed the user 
option to 'xterm-update-cursor' to allow it to also control the cursor 
color, which I will do in a future patch.

  -- MJF

Message #14 received at 80091 <at> debbugs.gnu.org (full text, mbox):

From: Jared Finder <jared <at> finder.org>
To: Sean Whitton <spwhitton <at> spwhitton.name>
Cc: 80091 <at> debbugs.gnu.org
Subject: Re: bug#80091: [PATCH] Update cursor display using Xterm escape
 sequences
Date: Mon, 29 Dec 2025 09:37:46 -0800

[Message part 1 (text/plain, inline)]

This time with the patch actually attached.

On 2025-12-29 09:37, Jared Finder wrote:
> On 2025-12-29 03:43, Sean Whitton wrote:
>> Hello,
>> 
>> On Sun 28 Dec 2025 at 07:14pm -08, Jared Finder wrote:
>> 
>>> This patch adds a user option to xterm.el, xterm-set-cursor-type, 
>>> which
>>> enables sending xterm escape sequences to update the way the cursor 
>>> is
>>> displayed.  Many modern terminals support escape sequences to switch 
>>> the
>>> cursor between a filled box, a vertical bar, and a horizontal bar.
>>> 
>>> I put this behind a user option because instead of capability 
>>> checking because
>>> the patch achieves this using post-command-hook.
>> 
>> Thanks.  This needs documenting in NEWS and possibly also the manual.
> 
> Updated patch attached.
> 
>> Can you recommend a terminal that supports this on GNU/Linux so I can
>> test the patch?
> 
> Try any of the following terminals:
> 
> Installable on Debian:
> * xfce4-terminal 1.1.4
> * gnome-terminal 3.56.2, VTE 0.80.1
> * konsole 25.04.2
> 
> Terminals on other OSes work too:
> * Windows Terminal (on Windows)
> * iTerm2 (on MacOS)
> 
> As an aside, all of these terminals except Konsole also appear to 
> support altering the cursor's color as well.  I've renamed the user 
> option to 'xterm-update-cursor' to allow it to also control the cursor 
> color, which I will do in a future patch.
> 
>   -- MJF

[0001-Update-cursor-display-using-Xterm-escape-sequences.patch (text/x-diff, attachment)]

Message #17 received at 80091 <at> debbugs.gnu.org (full text, mbox):

From: Sean Whitton <spwhitton <at> spwhitton.name>
To: Jared Finder <jared <at> finder.org>
Cc: 80091 <at> debbugs.gnu.org
Subject: Re: bug#80091: [PATCH] Update cursor display using Xterm escape
 sequences
Date: Tue, 30 Dec 2025 13:57:02 +0000

Hello,

Jared Finder [29/Dec  9:37am -08] wrote:
>> Try any of the following terminals:
>> Installable on Debian:
>> * xfce4-terminal 1.1.4
>> * gnome-terminal 3.56.2, VTE 0.80.1
>> * konsole 25.04.2

Thanks, I'll try it.

> diff --git a/doc/emacs/display.texi b/doc/emacs/display.texi
> index dd898e0cf88..f9665a59843 100644
> --- a/doc/emacs/display.texi
> +++ b/doc/emacs/display.texi
> @@ -2040,12 +2040,14 @@ Cursor Display
>
>  @vindex visible-cursor
>    On a text terminal, the cursor's appearance is controlled by the
> -terminal, largely out of the control of Emacs.  Some terminals offer
> -two different cursors: a visible static cursor, and a very
> -visible blinking cursor.  By default, Emacs uses the very visible
> -cursor, and switches to it when you start or resume Emacs.  If the
> -variable @code{visible-cursor} is @code{nil} when Emacs starts or
> -resumes, it uses the normal cursor.
> +terminal, largely out of the control of Emacs.  Some terminals offer two
> +different cursors: a visible static cursor, and a very visible blinking
> +cursor.  By default, Emacs uses the very visible cursor, and switches to
> +it when you start or resume Emacs.  If the variable @code{visible-cursor}
> +is @code{nil} when Emacs starts or resumes, it uses the normal cursor.  On
> +many Xterm compatible terminals, the cursor's type can be changed by Emacs
> +as well.  If the user option @code{xterm-set-cursor-type} is set, Emacs
> +updates the cursor's type similar to how it does so on graphical displays.
>
>  @vindex cursor-type
>    On a graphical display, many more properties of the text cursor can

Here you're introducing a forward-reference because the notion of a
cursor type is introduced right below.  Forward-references like that are
generally bad.  So I think your new text needs to be further down,
perhaps in its own paragraph.

Also, in all the docs, it should be "Xterm-compatible" not "Xterm
compatible".

> ++++
> +** New user option 'xterm-update-cursor' to update cursor display on TTYs.
> +When enabled, Emacs send Xterm escape sequences on Xterm compatible TTYs
> +to update the cursor's appearance based on 'cursor-type', similar to how
> +the cursor appears on graphical displays.  See the Info node "(emacs) Cursor
> +Display" for more information.

It might be worth mentioning here something like "For example if you
usually use a bar cursor on graphical displays then Emacs will use a bar
cursor in compatible text frames, too." because "cursor type" might not
be meaningful on its own to someone not familiar with the feature.

> +
>  
>  * Editing Changes in Emacs 31.1
>
> diff --git a/lisp/term/xterm.el b/lisp/term/xterm.el
> index e7469263036..1cb3495063c 100644
> --- a/lisp/term/xterm.el
> +++ b/lisp/term/xterm.el
> @@ -80,6 +80,11 @@ xterm-store-paste-on-kill-ring
>    :version "28.1"
>    :type 'boolean)
>
> +(defcustom xterm-update-cursor nil
> +  "If non-nil, update the cursor to match `cursor-type'."

Maybe "... try to update the text terminal cursor to match ...".

> +
> +Cursor type symbols are the same as for `cursor-type'.")
> +
> +(defun xterm--set-cursor-type (terminal type)
> +  (let ((type-int (or (plist-get xterm--cursor-type-to-int type) 1))
> +        (old (terminal-parameter terminal 'xterm--cursor-style)))
> +
> +    (when old
> +      (set-terminal-parameter terminal 'tty-mode-set-strings
> +                              (delete (format "\e[%d q" old)
> +                                      (terminal-parameter terminal 'tty-mode-set-strings))))

Please rearrange to avoid this long line.

-- 
Sean Whitton

Message #20 received at 80091 <at> debbugs.gnu.org (full text, mbox):

From: Sean Whitton <spwhitton <at> spwhitton.name>
To: Jared Finder <jared <at> finder.org>
Cc: 80091 <at> debbugs.gnu.org
Subject: Re: bug#80091: [PATCH] Update cursor display using Xterm escape
 sequences
Date: Tue, 30 Dec 2025 14:07:56 +0000

Hello again,

Jared Finder [29/Dec  9:37am -08] wrote:
>    ;; We likewise unconditionally enable support for focus tracking.
>    (xterm--init-focus-tracking))
>
> +(defun xterm--post-command-hook ()
> +  "Hook for xterm features that need to be frequently updated."
> +
> +  (unless (display-graphic-p)
> +    (when xterm-set-window-title
> +      (xterm-set-window-title))
> +    (when xterm-update-cursor
> +      (xterm--update-cursor-type))))
> +
>  (defun terminal-init-xterm ()
>    "Terminal initialization function for xterm."
>    (unwind-protect
> @@ -1052,7 +1068,7 @@ xterm--init-frame-title
>    (xterm-set-window-title)
>    (add-hook 'after-make-frame-functions 'xterm-set-window-title-flag)
>    (add-hook 'window-configuration-change-hook 'xterm-unset-window-title-flag)
> -  (add-hook 'post-command-hook 'xterm-set-window-title)
> +  (add-hook 'post-command-hook 'xterm--post-command-hook)
>    (add-hook 'minibuffer-exit-hook 'xterm-set-window-title))

This changes the logic in that previously xterm-set-window-title was
unconditionally added to post-command-hook but now it's guarded by both
(display-graphic-p) and xterm-set-window-title.
Are you sure that is okay to do?

-- 
Sean Whitton

Message #23 received at 80091 <at> debbugs.gnu.org (full text, mbox):

From: Jared Finder <jared <at> finder.org>
To: Sean Whitton <spwhitton <at> spwhitton.name>
Cc: 80091 <at> debbugs.gnu.org
Subject: Re: bug#80091: [PATCH] Update cursor display using Xterm escape
 sequences
Date: Tue, 30 Dec 2025 11:48:46 -0800

[Message part 1 (text/plain, inline)]

On 2025-12-30 06:07, Sean Whitton wrote:
> Hello,
> 
> Jared Finder [29/Dec  9:37am -08] wrote:
>>> Try any of the following terminals:
>>> Installable on Debian:
>>> * xfce4-terminal 1.1.4
>>> * gnome-terminal 3.56.2, VTE 0.80.1
>>> * konsole 25.04.2
> 
> Thanks, I'll try it.

New patch attached for prior feedback.  It also was easy to add support 
for updating the cursor color so I added that to the patch.  All the 
terminals I tested also support updating the cursor color except Konsole 
which does not support OSC 12 at all.

> Jared Finder [29/Dec  9:37am -08] wrote:
>>    ;; We likewise unconditionally enable support for focus tracking.
>>    (xterm--init-focus-tracking))
>> 
>> +(defun xterm--post-command-hook ()
>> +  "Hook for xterm features that need to be frequently updated."
>> +
>> +  (unless (display-graphic-p)
>> +    (when xterm-set-window-title
>> +      (xterm-set-window-title))
>> +    (when xterm-update-cursor
>> +      (xterm--update-cursor-type))))
>> +
>>  (defun terminal-init-xterm ()
>>    "Terminal initialization function for xterm."
>>    (unwind-protect
>> @@ -1052,7 +1068,7 @@ xterm--init-frame-title
>>    (xterm-set-window-title)
>>    (add-hook 'after-make-frame-functions 'xterm-set-window-title-flag)
>>    (add-hook 'window-configuration-change-hook 
>> 'xterm-unset-window-title-flag)
>> -  (add-hook 'post-command-hook 'xterm-set-window-title)
>> +  (add-hook 'post-command-hook 'xterm--post-command-hook)
>>    (add-hook 'minibuffer-exit-hook 'xterm-set-window-title))
> 
> This changes the logic in that previously xterm-set-window-title was
> unconditionally added to post-command-hook but now it's guarded by both
> (display-graphic-p) and xterm-set-window-title.
> Are you sure that is okay to do?

I'm not sure I follow.  I don't see the behavior change pointed out 
here.

Prior to my patch, the function xterm-set-window-title was only added to 
post-command-hook if xterm--init-frame-title was called, which only 
happened if the user option xterm-set-window-title is enabled while 
xterm--init is run.  The behavior with my patch is the same, only 
xterm--post-command-hook is added instead.

Maybe you're referring to running xterm-set-window-title as part of 
post-command-hook?  This is also unchanged.  Prior to my patch 
xterm-set-window-title internally guarded itself with display-graphic-p.

  -- MJF

[0001-Update-cursor-display-using-Xterm-escape-sequences.patch (text/x-diff, attachment)]

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