bug#52085: 29.0.50; Frame occasionally fails to paint while screen sharing on macOS

[Aaron Jensen <aaronjensen@gmail.com>]

On Thu, Dec 2, 2021 at 5:22 PM Alan Third <alan@idiocy.org> wrote:
>
> On Wed, Nov 24, 2021 at 08:12:53PM -0500, Aaron Jensen wrote:
> > I still need to try this with emacs -Q, but I have seen this for some
> > time now (possibly since Alan's recent batch of changes to macOS
> > rendering)
> >
> > If I am screen sharing on zoom, I will often issue a command that I
> > expect to repaint the frame and it will not. If I issue another then it
> > repaints immediately with both commands having been realized. This
> > *only* happens when screen sharing with Zoom. I will try other screen
> > sharing software to see if it is a Zoom specific thing. I am typically
> > sharing just the Emacs window (and maybe an iTerm and a browser), but
> > never full screen sharing.
> >
> > Alan, is there anything that you could think of that could cause
> > something like this to happen? Is there logging I could add to help get
> > to the bottom of it?
>
> Probably the first thing you could do is check that [EmacsLayer
> display] is being called at the right time.
>
> But I can't really think of any particular reason for this to happen.

How do I enable and observe NSTRACE?