T60: fallback fonts, which a user asked for after 0.1.6: font_fallbacks lists installed families the terminal tries in order for a character Font family lacks, through gpui's Font::fallbacks; each must load as the terminal draws it; Settings › Appearance lists them under Family, each a FontPicker with a remove button, then Add fallback

tasks/acceptance.md

@@ -63,6 +63,7 @@ What no check reached: no real KWin drew the blur; of Wayland desktops, only Hyp
 | Colors, styles, five underlines, wide characters, combining marks | T06 | `term::frame`, `term::ink`, `term::paint` tests | Pass |
 | Box drawing, blocks and powerline shapes as geometry | T07 | `term::boxes` tests | Pass |
 | JetBrains Mono, any installed font, Nerd Font icons | T06, T17 | `tests/fonts.rs` | Pass |
+| Fallback fonts: installed families tried in order for a character the family lacks, listed under Family in Settings › Appearance | T60 | `settings` test: a file without `font_fallbacks` loads with none, named families keep their order, and an empty one is refused; on macOS with Menlo and `"font_fallbacks": ["Kaiti SC"]` the terminal drew `中文字体 終端` in Kaiti and Latin in Menlo, where without it the system drew them in PingFang; a fallback gpui cannot load, `No Such Font`, stopped the start with `font_fallbacks: the terminal cannot load "No Such Font"`, and an empty one with `font_fallbacks holds an empty family`; in Settings › Appearance, Add fallback opened an empty picker, picking Kaiti SC saved `["Kaiti SC"]` and the terminal took it at once, the row's X saved `[]`, and Apple Color Emoji, which gpui loads no font for, was refused and nothing saved | Pass |
 | Cursor shapes, blink by setting and DECSCUSR, hollow unfocused | T06 | T06 review | Pass |
 | xterm keys, cursor mode, Option as Alt, kitty protocol, keypad; a shifted symbol as its own key with Shift on macOS and Windows; win32-input-mode on Windows | T08, T44 | `term::keys` tests, `kitty_reports_the_key_shift_turned_into_a_symbol` red at `CSI 123;13u` before the fix; on macOS herdr 0.9.5, its `[keys]` `previous_workspace = "cmd+shift+ctrl+["` and `next_workspace = "cmd+shift+ctrl+]"`, run by `shot` in a fresh HOME: before, ⌘⇧⌃] sent `CSI 125;13u` and herdr stayed on its workspace; after, `CSI 93:125;14u` moved it to the next and ⌘⇧⌃[, `CSI 91:123;14u`, back; `term::win32` and `term::tap` tests on Windows | Pass |
 | IME: marked text at the cursor, commits to the program | T08 | T08 review | Pass |