Re: macOS metal rendering engine in mac port

[Y . E .]

>> > It's infrequent, but I've seen a number of rendering artifacts in 28
>> > in the last month or so. Typically it is a line of group of lines that
>> > are painted twice (i.e. in the wrong place). I may see line 33
>> > duplicated so there is no 34, just two 33 in a row. Scrolling to
>> > change the position does not fix it. I have to scroll the buggy line
>> > out of view entirely and scroll it back to get it to be right.
>> >
>> > I do not have a repro for this unfortunately.
>>
>> I can confirm that I have been having this exact issue for quite some
>> time now. It is very infrequent and mild so I never bothered to report
>> it.
>>
>> I also don't have any ideas what's causing it and how to reproduce it,
>> but M-x redraw-display RET fixes it straight away.

I saw this (or extremely similar) issue 2-3 times during the past month
on an oldish MacOS with vanilla Emacs, in buffers with ELisp code.

I looked as if chunk of the text (from this buffer) overlayed
another (correct) text. And it was impossible to remove that overlaying
text without reverting (AFAIR) the buffer.

Unfortunately, I also have no idea on how to reproduce the issue so far.