bug#75333: 31.0.50; Feature-Request: Always keep cursor's position when pixel scrolling

[Eason Huang <aqua0210@foxmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Eason Huang <aqua0210@foxmail.com>
>> Date: Sat, 04 Jan 2025 08:50:04 +0800
>> 
>> 
>> Recently, when the cursor is inside the screen, it's positon will not
>> move when pixel scrolling. But when the cursor touching the bording of
>> window, it's position begin to change.
>> 
>> expected:
>> 
>> 1. when the cursor(line) is closed to the border of window, partially-visible
>> the cursor
>> 2. when the cursor(line) is outside the window, hide the cursor
>> 3. wehn the cursor(line) is inside the window, show the cursor again
>> 
>> Or there already an option to enable this feature?
>> 
>> As I known, Apple Xcode and Microsoft Word have the same behavior as
>> describe above.
>
> Unlike other editors, Emacs' display engine was designed with the
> explicit requirement that the position of point (what you call
> "cursor") is always visible in the window.  So when the window is
> scrolled for some reason, Emacs moves point to bring it back into the
> visible portion of the window.  This behavior is coded and assumed all
> over the place, and is hard to change.  There's therefore no option
> for the behavior you expect.
>
> There was an effort in the past to provide such behavior as an option,
> but AFAIR it wasn't completed.  We did discuss some of the
> consequences of such behavior and identified some problematic
> decisions which will need to be made in various situations (e.g., what
> should happen when point is outside of the window and the user runs
> some command which modifies the buffer?), and I personally consider
> those issues we considered to be the tip of a very large iceberg.  See
> this discussion:
>
>   https://lists.gnu.org/archive/html/emacs-devel/2021-12/msg00328.html
>

Hi Eli,

Thanks for your explanation, it make sense.

-- 
Eason Huang