tabbed-wlroots

A nested Wayland compositor (built on wlroots) that presents several client apps as tabs in a single window on the host Wayland compositor. Each command-line argument launches one tab.

Building

The project builds with Meson + Ninja. On most distributions the non-wlroots dependencies are available in the standard repositories; wlroots is used from the system where one is installed, and otherwise is fetched and built automatically from a pinned source tarball (subprojects/wlroots.wrap).

meson setup build
meson compile -C build

The resulting binary is build/tabbed-wlroots.

Debian / Ubuntu

sudo apt install build-essential meson ninja-build pkg-config \
    libwayland-dev libwayland-bin wayland-protocols \
    libxkbcommon-dev libpixman-1-dev \
    libegl1-mesa-dev libgles2-mesa-dev

No wlroots package is needed: this project targets wlroots 0.19, while Debian/Ubuntu ship another version as a versioned package (e.g. libwlroots-0.20-dev on Debian >= trixie, pkg-config name wlroots-0.20), so Meson builds the bundled 0.19.1 instead (see below).

Arch

sudo pacman -S base-devel meson ninja pkgconf wayland wayland-protocols \
    wlroots xkbcommon mesa pixman

Fedora

sudo dnf install gcc meson ninja-build pkgconf-pkg-config \
    wayland-devel wayland-protocols-devel wlroots-devel \
    libxkbcommon-devel mesa-libEGL-devel mesa-libGLES-devel pixman-devel

When the system wlroots dep is missing / the fallback can't find one

The Meson setup searches for wlroots-0.19 then wlroots; if neither is installed it builds the pinned 0.19.1 from subprojects/wlroots.wrap, which only needs the wayland, wayland-protocols, xkbcommon and EGL/GLES2 dev packages listed above. On newer Debian/Ubuntu the packaged wlroots is a versioned library (e.g. libwlroots-0.20-dev, pkg-config wlroots-0.20) whose version falls outside this project's >=0.19,<0.20 pin, so the fallback build is used automatically and no wlroots package needs to be installed. Optional wlroots features (Vulkan, X11, libinput, etc.) are auto-detected and skipped when their build deps aren't present, so a minimal install works too.

Usage

tabbed-wlroots [prog...]

Each <prog> is one shell command; quote it when it takes arguments, e.g. tabbed-wlroots "foot -e htop" "firefox -no-remote". With no arguments, a single terminal tab is opened (see $TERMINAL below). tabbed-wlroots -h prints this usage.

Every argument starts a new tab. There is no tab-count limit. Client apps run as children of tabbed-wlroots and connect to its private Wayland socket, so DISPLAY is unset for them and their WAYLAND_DISPLAY points at the tabbed compositor (clients are launched with the GDK and Qt Wayland backends forced).

Ctrl+Shift+T opens the terminal named by the $TERMINAL environment variable when it is set (see Key bindings); otherwise it falls back to alacritty. The value is used verbatim, so it may carry arguments, e.g. TERMINAL="foot -e htop" tabbed-wlroots ....

Notes:

An argument written bare (starting with -) is taken as a tab launcher too (unless quoted); a warning is printed when it looks like a stray option.
Each command (an argument or the default $TERMINAL) is resolved on PATH before the session starts: if its program isn't found, tabbed-wlroots prints an error and exits non-zero without opening any window.
The client applications run inside the session, so closing their windows only closes their tab; closing the host tabbed-wlroots window, or sending SIGINT/SIGTERM, shuts the whole session down and kills all client children.

Key bindings

Key	Action
`Alt` (hold)	Show the tab-title overlay (centered)
`Alt+Up`	Previous tab (hold to keep cycling)
`Alt+Down`	Next tab (hold to keep cycling)
`Ctrl+Shift+T`	Open a new terminal tab next to the current one

Holding Alt shows a passive overlay listing every tab's title with the active tab highlighted; the list updates live as you cycle with Up/Down and disappears on Alt release. It is drawn by tabbed itself, so it works on hosts with or without a title bar (the overlay text uses a system font via FreeType; set TABBED_FONT to pick one). Each row also shows the tab's app icon, resolved from its Wayland app_id via the desktop files and icon themes in XDG_DATA_DIRS (PNG via libpng, SVG via librsvg); tabs without a resolvable icon get a generic placeholder.

Ctrl+Shift+T launches a fresh terminal ($TERMINAL, default alacritty) as a new tab placed immediately to the right of the current tab, and it becomes the active tab once it maps — exactly as if its command had been given on the command line.

The tab-cycling hotkey only emits a physical press for the first tab switch; repeats are synthesized, so holding Alt+Up/Down keeps stepping through tabs while any other key stops it.

Function keys are not grabbed: F9/F10/F11 (and anything else) are forwarded to the focused client, so apps keep their own bindings (e.g. a browser's F11).

Fullscreen

Fullscreen mirrors between the host window and the clients:

Fullscreen the tabbed window (use your host compositor's fullscreen keybinding, or an app's own F11) and every tab is told it is fullscreen, so clients drop their decorations and fill the screen.
A client that requests fullscreen itself (e.g. a video player) also fullscreens the tabbed host window.
Leaving fullscreen returns every tab to maximized.

Logging (`TABBED_LOG`)

Quiet by default: a plain launch prints nothing to the launching terminal except fatal errors. Set TABBED_LOG before starting:

Value	Meaning
unset/`0`	Quiet. Only fatal errors are shown.
`1`	Info. Status lines, dump summaries, host notes (e.g. socket).
`2`	Debug. Adds a per-frame `[diag]` trace and EGL/render/import messages, and client stdout/stderr flows through.

At debug level (2) client programs also inherit the launching terminal's stdout/stderr instead of being silenced, which makes client errors visible.

Frame dumps (SIGUSR1 / TABBED_AUTODUMP)

The SIGUSR1 signal and TABBED_AUTODUMP write raw P6 portable-pixmap files to /tmp regardless of the log level:

SIGUSR1 writes /tmp/scene_N.ppm — the composed scene (whatever tabbed-wlroots rendered for the host).
SIGUSR1 also writes /tmp/host_N.ppm — the host compositor's back buffer, so you can see what the host actually displayed.
N is an incrementing per-run counter; a single SIGUSR1 produces a matching scene/host pair.
With TABBED_AUTODUMP (any value, e.g. TABBED_AUTODUMP=1), a scene and host dump are taken automatically once the first frame in which a client committed a CPU-readable (shared-memory) buffer — handy for capturing exactly what a newly launched client drew.
At TABBED_LOG=2 the diagnostic that detects the client's own shm buffer additionally writes that buffer to /tmp/client_N.ppm.

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