Rill

Rill is a Kryon/libdraw desktop shell for Taiji and Plan 9.

The project keeps shell behavior outside Kryon. Kryon provides the UI runtime, renderer backends, widgets, and reusable platform primitives; Rill owns panels, launchers, task/window presentation, desktop surfaces, settings, and platform adapters.

Current support

• Shared shell state model.
• Platform service interface for launcher/task/session operations.
• Linux adapter targeting XLibre-compatible X11 desktops through EWMH task discovery, focus, and close requests, with plan9port/libdraw for the UI.
• Linux application discovery from XDG .desktop files. Rill does not keep a hard-coded C launcher list for Linux.
• Plan 9 adapter using native launcher commands and rio window controls.
• Configurable Rill panel with Applications, task buttons, workspace pager and clock.
• Optional Wayland task discovery/focus/close through wlr foreign-toplevel management.
• Persistent panel layouts, including native Plan 9 save recovery.
• Desktop icons populated from discovered launchers marked X-Rill-Favorite=true.
• Kryon app hosts such as ktrem and Shelf can be exposed through .desktop launchers using Exec=host:<id>.
• Linux X11 window-manager mode with --wm.
• Contained windowed mode with --windowed, which starts a private Xvfb display and mirrors real X11 client windows into Rill.

Linux Launchers

The Linux target reads launchers from .desktop files instead of hard-coding applications in Rill. Discovery order is:

1. RILL_APPLICATION_DIRS, as a colon-separated list of directories.
2. $XDG_DATA_HOME/applications, or $HOME/.local/share/applications.
3. $XDG_DATA_DIRS/applications, or /usr/local/share/applications and /usr/share/applications.

Rill reads ordinary Desktop Entry application files with Type=Application, Name, Exec, Icon, Comment, and Categories. It honors localized names, TryExec, desktop visibility and user overrides. Hidden and NoDisplay entries are skipped; terminal applications are supported. GIO handles ordinary desktop launches, including field codes and working directories. The Exec command may also use Rill commands such as internal:settings or host:ktrem; those are handled by the shell before falling back to the platform launcher.

Two optional keys are recognized:

X-Rill-ID=terminal
X-Rill-Favorite=true

X-Rill-ID gives the launcher a stable Rill-facing ID. X-Rill-Favorite places the launcher on the desktop. Packages or user config should provide these files for Rill-specific built-ins; the Linux platform code should not grow a fixed launcher table.

XFCE Compatibility

Rill's native panel items are described through include/rill_panel.h. That is the extension point for Rill panel configuration and native Rill panel modules.

Run build/linux-x86_64/rill --desktop --xfce-panel in an X11 session to use Rill's desktop with the real installed Xfce panel and its plugin host. This requires an existing window manager and session D-Bus. It suppresses Rill's own panel; GTK plugins are hosted by Xfce, not embedded into Rill widgets.

An X11 login session is also available through scripts/rill-session, with Xfce session services and Rill crash restart/logout integration. make install installs its login entry. The separate session profile imports existing Xfce preferences on first launch. All 37 locally installed Xfce plugin modules passed load, resize/orientation and panel-restart checks; see the plugin validation.

Full Xfce replacement parity is not implemented. Native Wayland desktop surfaces, native session lifecycles, many desktop services and exhaustive plugin testing remain. See the compatibility report for the platform matrix, remaining work and verification commands.

Build

The default backend is libdraw so the Linux build exercises the same visual path intended for Plan 9:

make

Override paths when needed:

make KRYON_DIR=/mnt/storage/Projects/kryon \
     PLAN9PORT_DIR=/mnt/storage/Projects/plan9port

Run tests:

make test

Run the contained X11 smoke test:

make windowed-smoke

Run Rill under plan9port/devdraw:

make run

Run Rill as an X11 window manager on the current display:

build/linux-x86_64/rill --wm

Run Rill as a contained virtual display inside an ordinary desktop window:

build/linux-x86_64/rill --windowed xterm

Native Plan 9 uses Kryon's native mkfile plus Rill's Plan 9 adapter. In Taiji, /sys/src/cmd/rill installs the system desktop command.

Complete desktop in a window

scripts/rill-window --size 1280x800

This starts a real Xephyr X server in one host X11/XLibre window, then runs the Rill session, our rill-wm window manager, Xfce panel/plugins and applications on its separate display. Closing the outer window stops the nested session; logging out closes it too. The window is resizable and Rill follows the inner display size.

Install Xephyr (xserver-xephyr on Debian) and the session dependencies above. Set RILL_XEPHYR=/path/to/Xephyr to use a local server binary. make install also installs rill-window. The nested server chooses an available display, uses a private Xauthority cookie, disables TCP listening, and starts the session with its own D-Bus bus and runtime directory. This is a nested desktop on the same machine, not a virtual machine.

The older rill --windowed uses Xvfb and Rill's experimental window capture and input forwarding. Use rill-window for the complete session and standard X11 input/window handling. Clipboard and drag/drop between the outer and inner desktops are not bridged automatically. GPU/GLX behavior and global shortcut capture depend on the nested server and host; they are not certified by the basic smoke test.

make nested-smoke checks separate inner/outer window trees, desktop resizing, application launch inside the inner server, crash restart and logout. It needs Xephyr, xdotool and the existing session-test dependencies.

Rill window manager

make builds the standalone rill-wm. It is now the default WM in rill-session and rill-window. It manages real X11 application windows with native input, decorations, workspaces, panel work areas and XRender compositing. See window-manager behavior and compatibility for shortcuts, validation and the remaining gaps before xfwm4 parity.

Use RILL_WM=xfwm4 scripts/rill-window for the previous WM, or RILL_WM_COMPOSITE=0 scripts/rill-window to disable Rill's compositor. The older rill --wm is an experimental capture path; it is separate from rill-wm.

New sessions import your existing Xfce panel layout, pinned launchers and wallpaper. With no existing layout, Rill creates a single 26-pixel top panel; it does not add a bottom dock. Imported layouts and later Rill customizations are preserved.