On Sun, Mar 23, 2025 at 3:37 AM, Eli Zaretskii <eliz@gnu.org> wrote:

Cc: gerd.moellmann@gmail.com, alan@idiocy.org, 77039@debbugs.gnu.org Date: Sun, 23 Mar 2025 12:13:10 +0200
From: Eli Zaretskii <eliz@gnu.org>

So in summary, I don't see anything abnormal here. If we want to keep the only-current-line-changed optimization in redisplay_internal, someone will have to come up with a smarter test for when line numbers are shown. I think the underlying problem is that when the line number of the current line becomes large enough to require more columns for line-number display, we must redraw the entire window to avoid the problem with shifting or line number described in https://debbugs.gnu.org/cgi/bugreport.cgi?bug=54091#5 .

To clarify: this should not cause any flickering, AFAIU, because the comparison of glyphs in subroutines of update_frame is supposed to find that everything on the glass is already up-to-date and there's no need to draw anything. So flickering, which happens because portions of the window are actually redrawn on the glass, should not happen in this case.


Right, I don't observe any flickering. Am I correct that it is only comparing the glyphs on the current line? If so, that doesn't seem like a huge problem, even though it is (in most cases?) technically extra work.

Aaron