[bug]: Incorrect background color of cells leading to crash

[pkazmier]

Shortly after increasing the size of my font while in Neovim, ghostty will get into a state where the background color of some cells is incorrect. I'm able to reproduce this consistently every time. Some times, if I don't restart ghostty, it'll then lead to a crash. I am on macOS and run tip. I update every day and this started a few days ago.

Here is a video to demonstrate. The first 5 seconds shows normal behavior as I try to enter this corrupted state. You'll see me in neovim performing a visual selection and opening my picker where things are working correctly. But at the 5 second mark, you can see something changes. The visual selection is broken. The picker has weird blocks of color. I open lazygit inside vim and the colors are all screwed up.

https://youtu.be/R-ITrvDzlXE

And, as mentioned above, sometimes when I get into this state, ghostty will crash. I cannot reproduce that as often. But the visual blocking can easily be reproduced—typically with 5-10 seconds of me opening a fresh terminal. And once in this state, even if I'm not in Neovim, the artifacts persist. For example, if I open htop, it will exhibit them as well.

Ghostty 1.0.2-main+72d08552

Version
  - version: 1.0.2-main+72d08552
  - channel: tip
Build Config
  - Zig version: 0.13.0
  - build mode : builtin.OptimizeMode.ReleaseFast
  - app runtime: apprt.Runtime.none
  - font engine: font.main.Backend.coretext
  - renderer   : renderer.Metal
  - libxev     : main.Backend.kqueue

On the Discord server, I've also posted an asciinema cast as well.

[pkazmier]

I've narrowed down the commit when this started to exhibit itself: fca336c

And, I've narrowed down that it has something to do with smear-cursor. It seems to be related to the fast drawing of the smear while large parts of the screen are being redrawn when I open a popup in Neovim for example. If I disable this plug-in, the problem goes away.

I compiled a debug build, but there is nothing interesting in the logs that I saw.

[pkazmier]

This issue was resolved in #4523.