There are two user-visible changes in here:
1. If a scroll region is set such that there is a bottom margin and no
top margin, scrolling the region forward used to discard the top
lines. Now those lines are appended to the scrollback.
```shell
# Assuming a terminal window with 24 lines.
printf '\033[H\033[J\033[3J\033[0;5r' && seq 100
```
This command used to result in an empty scrollback. Now it contains
the numbers 1-96.
2. If a scroll region is set such that there is a top margin and no bottom
margin, scrolling the region forward used to append the top lines to
the scrollback. Now these lines are discarded.
```shell
# Assuming a terminal window with 24 lines.
printf '\033[H\033[J\033[3J\033[2;24r' && seq 100
```
This command used to populate scrollback with the numbers 2-78. Now
the scrollback is empty. The numbers on the screen are the same as
before: 1 and 79-100.
Related issue: #3113.
The scheme used in draw_sextant works well enough, but the
feed was broken. 21 and 42 need to be skipped, not 20 and
40. Without this change, the following glyphs are broken:
U+1FB13 BLOCK SEXTANT-35 🬓 renders as LEFT HALF
U+1FB26 BLOCK SEXTANT-46 🬦 renders as SEXTANT-146
U+1FB27 BLOCK SEXTANT-146 🬧 renders as RIGHT HALF
With this change, the entirety of the sextant block works
correctly. Found debugging the Notcurses sextant blitter:
https://github.com/dankamongmen/notcurses/issues/1112
This makes it possible to execute `nix-shell` to create the correct environment to build kitty. Use `nix-shell --pure` to eliminate most of the influence of the outside system, e.g. globally installed packages.
This works on NixOS and any Linux or macOS system with the Nix package manager installed.
The build inputs are split into `buildInputs`, `nativeBuildInputs`, `propagatedBuildInputs` and `checkInputs` so it closely resembles 2bb3a9da24/pkgs/applications/terminal-emulators/kitty/default.nix. This makes it easy to port changes between the two files.
On Wayland, some compositors refuse to implement SSDs in which case we draw
primitive CSDs. However, the destructors were called in the wrong order,
leading to a dereference of an already freed object.
