T20: on Wayland the window asks for ext_background_effect_v1 on its surface, through a guest connection on gpui's display; one region wider than any window, which the compositor clips, comes and goes with Blurred; the log names the way blur goes; a wayland-server compositor tests it, and scripts/linux.sh runs the tests on Linux in a container

scripts/linux.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+# linux.sh ARGS: runs `cargo ARGS` on the working tree in a Linux container.
+set -eu
+repo=$(cd "$(dirname "$0")/.." && pwd)
+docker build -q -t elyterminal-linux - >/dev/null <<'EOF'
+FROM rust:1.95
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends pkg-config libwayland-dev libxkbcommon-dev \
+    libxkbcommon-x11-dev libxcb1-dev libx11-xcb-dev libfontconfig-dev libfreetype-dev zsh fish \
+ && rm -rf /var/lib/apt/lists/* \
+ && rustup component add clippy rustfmt
+# Root ignores the file modes the tests check, as in CI.
+RUN useradd --create-home ci \
+ && mkdir -p /src /target /usr/local/cargo/registry /usr/local/cargo/git \
+ && chown ci /src /target /usr/local/cargo/registry /usr/local/cargo/git
+USER ci
+ENV CARGO_TARGET_DIR=/target CARGO_PROFILE_DEV_DEBUG=0 CARGO_INCREMENTAL=0
+WORKDIR /src
+EOF
+# Streamed, not shared, and dated now: cargo neither reads a stale file nor skips a changed one.
+git -C "$repo" ls-files -co --exclude-standard -z |
+  COPYFILE_DISABLE=1 tar -C "$repo" --null -T - -cf - |
+  docker run -i --rm \
+    -v ely-linux-target:/target \
+    -v ely-linux-registry:/usr/local/cargo/registry \
+    -v ely-linux-git:/usr/local/cargo/git \
+    elyterminal-linux sh -c 'tar -xmf - -C /src && exec cargo "$@"' cargo "$@"