Re: 23.0.60; Constant recentering with scroll-margin set

Re: 23.0.60; Constant recentering with scroll-margin set

[Chong Yidong]

Ralf Angeli <angeli@caeruleus.net> writes:

> * Ralf Angeli (2008-08-07) writes:
>
>> It could also be that this has to be fixed in Gnus.  I'm not sure, but I
>> remember that there was a similar issue back in 2005 where some changes
>> hat to be made in `gnus-article-next-page' and related functions in
>> order to deal with some changes in the handling of `scroll-margin'.
>
> Okay, the problem is the statement
> (move-to-window-line -1)
> in `gnus-article-next-page'.  If `scroll-margin' is set and greater than
> 0 it will lead to a recentering.  This is usually countered by
> `gnus-article-next-page-1', but not at the end of an article where
> `gnus-article-next-page-1' will not be called.
>
> The problem can be circumvented by changing the above statement to
> (move-to-window-line (- -1 scroll-margin))
>
> Let me know if the recentering behavior will stay like it is now, then
> I can report this to the Gnus maintainers.

What do people think?  When there is a scroll-margin, should
move-to-window-line automagically move to the scroll-margin instead of
recentering?

Re: 23.0.60; Constant recentering with scroll-margin set

[Lennart Borgman (gmail)]

Chong Yidong wrote:
> Ralf Angeli <angeli@caeruleus.net> writes:
> 
>> * Ralf Angeli (2008-08-07) writes:
>>
>>> It could also be that this has to be fixed in Gnus.  I'm not sure, but I
>>> remember that there was a similar issue back in 2005 where some changes
>>> hat to be made in `gnus-article-next-page' and related functions in
>>> order to deal with some changes in the handling of `scroll-margin'.
>> Okay, the problem is the statement
>> (move-to-window-line -1)
>> in `gnus-article-next-page'.  If `scroll-margin' is set and greater than
>> 0 it will lead to a recentering.  This is usually countered by
>> `gnus-article-next-page-1', but not at the end of an article where
>> `gnus-article-next-page-1' will not be called.
>>
>> The problem can be circumvented by changing the above statement to
>> (move-to-window-line (- -1 scroll-margin))
>>
>> Let me know if the recentering behavior will stay like it is now, then
>> I can report this to the Gnus maintainers.
> 
> What do people think?  When there is a scroll-margin, should
> move-to-window-line automagically move to the scroll-margin instead of
> recentering?

Yes. Automatic recentering is very disturbing IMO.

Re: 23.0.60; Constant recentering with scroll-margin set

[Stefan Monnier]

> What do people think?  When there is a scroll-margin, should
> move-to-window-line automagically move to the scroll-margin instead of
> recentering?

I never used it, neither interactively nor programmatically, so I don't
have a strong opinion on that.  Reading the docstring I get the
impression that the intention is to place the cursor at a particular
location within the window, rather than to place point at a particular
location within the buffer.  So that leads me to think that it should
never cause recentering.  Maybe if the operation cannot be performed,
the function should return the number of lines "left".


        Stefan

Re: 23.0.60; Constant recentering with scroll-margin set

[Miles Bader]

Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> What do people think?  When there is a scroll-margin, should
>> move-to-window-line automagically move to the scroll-margin instead of
>> recentering?
>
> I never used it, neither interactively nor programmatically, so I don't
> have a strong opinion on that.  Reading the docstring I get the
> impression that the intention is to place the cursor at a particular
> location within the window, rather than to place point at a particular
> location within the buffer.  So that leads me to think that it should
> never cause recentering.  Maybe if the operation cannot be performed,
> the function should return the number of lines "left".

I use this function constantly -- I have simple wrappers bound to M-,
M-/ and M-. to move to the top, middle, and bottom of the window.

I almost never use a non-zero scroll-margin, so I don't have that much
experience with this problem, but I agree that it feels kind of weird if
move-to-window-line causes scrolling.

I kinda wish it would simply "disobey" the scroll-margin and locate the
cursor there without scrolling, but that probably isn't easy to
implement.

The suggested behavior of "stopping short", by having it move to line
(min (max N scroll-margin) (- window-height scroll-margin)) seems
reasonable interactively.

It might surprise some programmatic users, but on the other hand,
scrolling will probably surprise them too, so I guess there's really not
much you can do in that case; such code probably simply isn't prepared
to deal with a non-zero scroll-margin...

-Miles

-- 
`To alcohol!  The cause of, and solution to,
 all of life's problems' --Homer J. Simpson