feat(overlay): X11 layer support via _NET_WM_STATE_ABOVE #23

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opened 2026-07-28 16:25:06 +02:00 by elegos · 0 comments

elegos commented

2026-07-28 16:25:06 +02:00

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Summary

On X11, winit creates a standard window positioned by the window manager — no guarantee it appears above the DM session.

Proposed approach

Add an X11 path (separate x11_platform.rs) that:

Detects DISPLAY env var (and absence of WAYLAND_DISPLAY).
Uses x11rb or xcb to create a window with:
- _NET_WM_STATE_ABOVE for always-on-top
- _NET_WM_WINDOW_TYPE_NOTIFICATION or _NET_WM_WINDOW_TYPE_DIALOG
- override_redirect = 1 (optional, more aggressive for DM use)
Centers the window manually against screen dimensions.
Renders via Slint's MinimalSoftwareWindow + software renderer (same as Wayland path).

Notes

Scope: only activate when DISPLAY is set and WAYLAND_DISPLAY is unset.
DM targets: lightdm-gtk-greeter, SDDM X11 session.
GNOME/KDE compositors may honour _NET_WM_STATE_ABOVE differently; override_redirect is more reliable for DM use but bypasses compositing.
Lower priority than the Wayland path (SDDM Wayland + greetd are primary targets).

Feature flag

Add a x11 feature to linux-hello-overlay, disabled by default, following the same pattern as the existing wayland feature.

## Summary On X11, winit creates a standard window positioned by the window manager — no guarantee it appears above the DM session. ## Proposed approach Add an X11 path (separate `x11_platform.rs`) that: 1. Detects `DISPLAY` env var (and absence of `WAYLAND_DISPLAY`). 2. Uses `x11rb` or `xcb` to create a window with: - `_NET_WM_STATE_ABOVE` for always-on-top - `_NET_WM_WINDOW_TYPE_NOTIFICATION` or `_NET_WM_WINDOW_TYPE_DIALOG` - `override_redirect = 1` (optional, more aggressive for DM use) 3. Centers the window manually against screen dimensions. 4. Renders via Slint's `MinimalSoftwareWindow` + software renderer (same as Wayland path). ## Notes - Scope: only activate when `DISPLAY` is set and `WAYLAND_DISPLAY` is unset. - DM targets: lightdm-gtk-greeter, SDDM X11 session. - GNOME/KDE compositors may honour `_NET_WM_STATE_ABOVE` differently; `override_redirect` is more reliable for DM use but bypasses compositing. - Lower priority than the Wayland path (SDDM Wayland + greetd are primary targets). ## Feature flag Add a `x11` feature to `linux-hello-overlay`, disabled by default, following the same pattern as the existing `wayland` feature.

elegos added this to the Foundation project

2026-07-29 10:59:36 +02:00

elegos removed this from the Foundation project

2026-07-29 10:59:42 +02:00

elegos added this to the Foundation project

2026-07-29 11:00:02 +02:00

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2026-07-29 11:17:28 +02:00