bug#12927: 24.2; global-hl-line-mode and "scroll-conservatively=1000" take jump up-down the text when hold DOWN key (in *info* buffer).

[Oleksandr Gavenko]

On 2012-11-20, Eli Zaretskii wrote:

>> From: Oleksandr Gavenko
>> 
>> > Should be fixed in revision 110927 on the emacs-24 branch.  Please
>> > test.
>> 
>> I don't familiar with bzr:
>> 
>>   $ bzr up
>>   $ bzr info -v
>>           checkout of branch: bzr://bzr.savannah.gnu.org/emacs/trunk/
>>            shared repository: /home/user/devel/emacs/emacs-bzr
>
> This is the trunk, not the emacs-24 branch.  I committed the fix to
> the emacs-24 branch.  You can wait until the changes from the branch
> are merged onto the trunk, and test then.  Or you can checkout the
> branch, like so:
>
>   $ cd /home/user/devel/emacs/emacs-bzr
>   $ bzr branch bzr://bzr.savannah.gnu.org/emacs/emacs-24
>
I test on 'emacs-24' branch (based on your instruction) and confirm that bug
go away!

>> Also I found that "(global-hl-line-mode 1)" slow down scrolling in CC-mode
>> enabled buffers in two or more times. Do I need report a bug?
>
> No, this is expected.  hl-line-mode adds itself to post-command-hook,
> and moves its overlay after each command that changes the current
> line.  What this does is completely disable the redisplay
> optimizations used when only the cursor moves without any other
> changes to the text, because moving an overlay requires a thorough
> redisplay of the window, which is more expensive.
>
> The only bug report that I can think of is a feature request to move
> hl-line-mode into the display engine, because the display engine
> knowns very well where's the current line (when it decides where to
> display the cursor), and can do this highlighting better and much more
> efficiently.

OK. I would like to see hl-line-mode into the display engine. I would make
appropriate a bug report...

-- 
Best regards!