[Bug] Ghostty is able to scroll above vim split/window

[JacobCallahan]

I'm seeing some interesting behavior where I can scroll above the screen that vim renders. This is most consistently reproduced in a split, but I have also seen it in a fullscreen/tabbed instance of vim.

Issue Video
https://github.com/user-attachments/assets/aea80bdc-249e-45be-ae56-fafdcb6108c5

System Information

[mitchellh]

This very strongly looks like a terminfo issue of some sort. I've never seen this reported before. Do you have some method to reproduce?

[JacobCallahan]

Without any other system as a reference, I just have the reproducer steps described in the post.

Actually, I just tested with a few different things and noticed that some things like: btop, textual TUIs, and fzf don't reproduce the issue. However, others like: vim, top, and man do.

This may be due to the first group actively listening for mouse input while the second group doesn't (or at least doesn't in the same way).

[mitchellh]

This is odd because alt screen (the thing that things like vim use) doesn't have any scrollback to go into. The fact you can see your shell up there implies that the program is NOT switching to alt screen, which is why it seems like a terminfo issue to me somehow.

I've tried reproducing this with various programs and cannot.

[JacobCallahan]

That may explain some of the other issues I'm seeing when exiting "full screen" apps, like vim, where the previously rendered text from earlier commands is "blanked out" by the space used to render vim.
I'm afk for a while, but can record that as well, if you're interested.

[JacobCallahan]

Ok, I had a few minutes, so recorded what I probably didn't explain well.
Here's a more dramatic example of using less on a single line file and the resulting impact on what Ghostty renders.

2025-01-21_09-34-25.mp4

[dragonJACson]

Looks like this is a similar issue #4430, and we have some steps there to reproduce it both on Linux and macOS

[JacobCallahan]

It may be related, but appears to present a bit differently than what I've recorded.