bug#28874: display-line-numbers-mode and split window vertically

[Eli Zaretskii]

On October 17, 2017 2:53:15 PM GMT+03:00, Konrad Podczeck 
<konrad.podczeck@univie.ac.at> wrote:
> Wth the pretest 26.0.90 version (for a Mac, obtained from
> https://emacsformacosx.com/builds), I observe the following:
> 
> (a) open a file with more than 10000 lines.
> 
> (b) turn on display-line-numbers-mode
> 
> (c) scroll down to the end of the buffer and the back to the
> beginning, so that you see only a part of the buffer where all line
> numbers have just two digits
> 
> (d) now do Menu>File>New Window Below
> 
> Then the range where the line numbers appear shrinks. Removing the
> split by middle-mouse clicking on the splitting mode-line makes that
> range increases again. For me, this behaviour is not convincing. Now
> do Menu>File>New Window Below another time and then in the lower half
> of the spilt scroll down, and you end up with two parts which have
> different with of the ranges showing the line numbers, which, for me,
> looks rather ugly.

This is not a bug, but intended behavior.  If you don't like it, customize
display-line-numbers-grow-only to a non-nil value.