Compose Desktop runs on Wayland directly — no XWayland fallback, fractional scaling, real gestures.

On JBR, Linux Compose apps fall back to XWayland — fuzzy fractional scaling, no real gesture support, broken HiDPI on mixed displays. The Tao backend talks Wayland directly: real surfaces, real fractional scale, real wl_pointer_gestures.

TL;DR

Native wl_surface — no XWayland round-trip.
Fractional scaling via wp_fractional_scale_v1 (no 1x/2x staircase).
Multi-touch and pen via pointer-gestures-unstable-v1 and wp_tablet_v2.
Drag-and-drop via wl_data_device, client-side decorations via xdg-decoration.
Falls back to X11 transparently on legacy sessions.

Install

Bundled with decorated-window-tao.

Quickstart — detect the session

import dev.nucleusframework.core.runtime.Platform

val onWayland = Platform.isWayland
val desktopEnv = Platform.Current.let { if (it == Platform.Linux) LinuxDesktopFileDetector.detect() else null }

You won't typically branch on this — Compose code stays identical. But it's handy for diagnostics and feature gates (badges, taskbar progress, global hotkeys behave differently per session).

How it works

Tao binds the standard Wayland protocols at startup: xdg-shell for windows, xdg-decoration to negotiate server- vs client-side decorations, wp_fractional_scale_v1 for sub-integer scale factors, pointer-gestures-unstable-v1 for pinch/swipe, wp_tablet_v2 for stylus. Skiko renders to an EGL surface attached to that wl_surface.

When the compositor signals a scale change (the user drags your window between a 1.0 and 1.5 monitor), Tao reconfigures the EGL surface and emits a density change to Compose. Your Dp values stay logical; the rendered output goes crisp. See Per-monitor HiDPI for the details.

If you launch on an X11 session (or a Wayland compositor that refuses XDG decorations), Tao falls back to X11 automatically. The Compose code doesn't change.

Wayland vs X11 differences

Concern	Wayland (Tao)	X11 (fallback)
Fractional scaling	Native, per-output	Whole-pixel only
Window placement	Compositor-controlled	Client can set absolute position
Global hotkeys	Compositor-mediated (`xdg-portal`)	`XGrabKey`
Screen capture	Portal-only	Direct
Pen pressure	`wp_tablet_v2`	Not exposed
Multi-touch gestures	`pointer-gestures-unstable-v1`	Limited

Window placement on Wayland: you cannot set absolute screen coordinates — the compositor owns placement. WindowState.position is honoured by some compositors as a hint, ignored by others (GNOME, in particular, ignores client-requested positions). Build your layout around Center, PlatformDefault, or remember the last size only.

Reference

Platform.isWayland — true when WAYLAND_DISPLAY is set and the session is Wayland.
Platform.Current — Linux | Windows | MacOS | Unknown.
LinuxDesktopEnvironment and LinuxDesktopFileDetector — distinguish GNOME, KDE, Sway, etc.

Native Wayland