BigCedilla

A KWin/Plasma 6 input-method-v1 proxy that restores the Brazilian ç when a dead-acute key (' or ´) is followed by c — without disabling the on-screen keyboard (plasma-keyboard or Maliit).

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Why this exists

Chromium and its derivatives (Google Chrome, Brave, Edge, Opera, Vivaldi — anything that renders with WebContents) no longer accept the ' + c sequence as ç on Brazilian / US-International layouts under Wayland.

Expected behavior:

'  +  c   →   ç
'  +  C   →   Ç

Current behavior in Chromium:

'  +  c   →   ć   (U+0107, c with acute — Polish letter)

Cause: Chromium now combines the dead acute directly onto the c, ignoring the Brazilian XCompose rule that maps that sequence to ç (U+00E7). It affects both US-International with dead keys and pt-BR variants that emit dead_acute.

Other browsers (Firefox, WebKit/GNOME Web) still respect XCompose and are unaffected. Native GTK/Qt apps, IDEs and text editors keep working as expected. The regression is limited to Chromium and everything that inherits from it.

bigcedilla fixes the problem outside the browser, at the Wayland protocol layer — so it works for every app on the system, not only Chromium.

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How it works

┌─────────┐   IM v1    ┌─────────────┐   IM v1    ┌──────────────────┐
│  KWin   │ ─────────► │ bigcedilla  │ ─────────► │ plasma-keyboard  │
│ Plasma6 │            │   (proxy)   │            │ or maliit-kbd    │
└─────────┘ ◄───────── └─────────────┘ ◄───────── └──────────────────┘
                              │
                              │ intercept dead_acute + c
                              ▼
                     commit_string("ç") → KWin

1. KWin treats bigcedilla as the system input method (the [Wayland] InputMethod field in kwinrc).
2. bigcedilla opens its own private Wayland socket and starts the real on-screen keyboard (plasma-keyboard by default; switch to Maliit via BIGCEDILLA_CHILD_IM=maliit-keyboard).
3. Everything the on-screen keyboard emits is forwarded as-is. Touch typing keeps working.
4. In parallel, bigcedilla calls grab_keyboard on the IM context and runs hardware keysyms through a tiny compose state machine. Only the dead_acute + c sequence is intercepted and rewritten as commit_string("ç") (or "Ç" for capital c).
5. Every other key is replayed via context.key() so the focused app processes it normally — including its own XCompose, shortcuts, etc.

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Install

Arch / BigLinux / Manjaro

cd pkgbuild
makepkg -si

Then, as the desktop user (not root):

bigcedilla-configure-kwin
qdbus6 org.kde.KWin /KWin reconfigure

To revert at any time:

bigcedilla-restore-maliit
qdbus6 org.kde.KWin /KWin reconfigure

Manual build

cargo build --release
sudo install -Dm755 target/release/bigcedilla /usr/bin/bigcedilla
sudo install -Dm644 pkgbuild/bigcedilla.desktop \
    /usr/share/applications/bigcedilla.desktop
sudo install -Dm755 pkgbuild/bigcedilla-configure-kwin /usr/bin/
sudo install -Dm755 pkgbuild/bigcedilla-restore-maliit /usr/bin/

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Configuration

Environment variable	Effect
BIGCEDILLA_CHILD_IM	Path or basename of the child on-screen keyboard. Default: plasma-keyboard, fallback maliit-keyboard. Set to maliit-keyboard to force Maliit when both are installed.
BIGCEDILLA_FORCE	1 always activate, 0 always skip. Bypasses the layout/locale check.
RUST_LOG=debug	Verbose log (includes keysyms — local debugging only).

Layout / locale gating

bigcedilla-check-layout decides whether the proxy is useful for the current account. It returns success when any of the following holds:

• LANG / LC_* matches pt_*, ca_*, oc_*, fur_*
• KDE kxkbrc (or localectl / setxkbmap fallback) reports a layout in {br, pt, ca, oc}
• a us layout uses an intl or altgr-intl variant

It is wired in two places:

• The user systemd unit (pkgbuild/bigcedilla.service) calls it as ExecCondition= — if the layout does not benefit, the unit silently exits without spawning the proxy.
• bigcedilla-configure-kwin refuses to register bigcedilla as the KWin input method when the check fails, unless invoked with --force or BIGCEDILLA_FORCE=1.

Layouts with ç as a direct key (French AZERTY, Turkish, Albanian, Azeri, Tatar) are intentionally skipped — they were never affected by the Chromium regression.

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Requirements

• KWin / Plasma 6 in a Wayland session
• plasma-keyboard or maliit-keyboard installed
• libxkbcommon, wayland

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License

GPL-3.0-or-later.