Subject: bug#32932: 27.0.50; render bugs on macOS Mojave

From: Eli Zaretskii <[email-masked]>
Date: Thu, 01 Nov 2018 20:10:53 +0200

> From: Aaron Jensen <[email-masked]>
> Date: Wed, 31 Oct 2018 23:51:42 -0700
> Cc: Alan Third <[email-masked]>, [email-masked]
> 
> getting set causes erase_phys_cursor to get called, which ultimately
> calls draw_phys_cursor_glyph, which calls draw_glyphs, which I believe
> is what is blanking the line. It appears to be more than just
> redrawing the glyph under the cursor.
> 
> Another clue is that it appear to only blank from where the cursor is
> to the end of the line. Anything before that isn’t cleared.

Can you find the reason for that?  In general, redrawing the cursor
should only redraw a single character, and sometimes the two adjacent
ones.  It shouldn't redraw more than that.

>From what you describe, it sounds like the problem is in the logic
that determines which parts to redraw, see update_text_area in
dispnew.c.