Subject: bug#63187: 30.0.50; Tail of longer lines painted after end of nearby lines on macOS

From: Eli Zaretskii <[email-masked]>
Date: Mon, 01 May 2023 15:40:36 +0300

> Cc: [email-masked]
> Date: Mon, 01 May 2023 07:58:26 +0800
> From:  Po Lu via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <[email-masked]>
> 
> Aaron Jensen <[email-masked]> writes:
> 
> > Is there anything specific to macOS that is involved in scrolling optimization?
> 
> Yes, Apple deleted the API used to perform bit blits, so Emacs uses a
> workaround that I don't really understand, and seems unreliable.

You mean, ns_scroll_run in nsterm.m?  Which parts of it do you not
understand?