#1151: Preferences › Performance › Linux display server opens the window through Xwayland, where file drops work

winit 0.30 delivers no file drops on native Wayland. The new Linux Display
Server preference (Automatic / X11 (XWayland), shown on Linux only, read at
startup) has winit open the window on X11 when the session is Wayland,
DISPLAY is set and the X11 libraries winit loads are installed (ldconfig
check ported from PhotoCraft); otherwise the window opens on Wayland and
the log says why. README, development notes, parity docs, ROADMAP and the
complete catalogs updated.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/development.md

@@ -102,8 +102,8 @@ The window runs natively on Wayland (eframe's `wayland` feature) and on X11. On
 - **Clipboard:** under Wayland arboard talks to the compositor through the data-control protocol (wlroots compositors such as Sway and Hyprland, KDE Plasma), so bitmaps (`image/png`), SVG markup and text copied in any app paste (#398). Where the compositor lacks the protocol (GNOME's Mutter, [arboard#223](https://github.com/1Password/arboard/issues/223)), arboard falls back to the X11 clipboard through XWayland, which only holds what X11 apps copied. egui's own text paste into fields goes through smithay-clipboard and works either way.
 - **Clipboard owners that never answer (#510):** reading the clipboard waits on the app that owns it: arboard gives up on an X11 owner after 4 s, and a Wayland read waits for the owner to send its data. So on Linux the check that enables the Paste menu items runs on a background thread with a second clipboard handle (`crates/ui-egui/src/clipboard_probe.rs`, installed as `Services::clipboard_probe`), only while nothing is copied in the app and a document is open, and the window keeps drawing. A paste itself still reads on the UI thread, so pasting from such an owner waits for it once. Windows and macOS keep the check on the UI thread: Windows only asks which formats the clipboard holds, macOS asks the pasteboard server.
 - **Copied files:** files copied in a file manager (`text/uri-list`; `CF_HDROP` on Windows, file URLs on macOS) paste as the first one that is art (SVG, PDF, EMF/WMF or a bitmap), before the clipboard's other formats (which include the files' paths as text).
-- **Dropping files on the window does not work under Wayland:** winit 0.30, which eframe 0.36 runs on, has no Wayland drag and drop ([winit#1881](https://github.com/rust-windowing/winit/issues/1881), added in winit 0.31; [egui#1563](https://github.com/emilk/egui/issues/1563)), so no `dropped_files` arrive. Until eframe moves to winit 0.31: copy the files in the file manager and paste them, use File › Place or Open, or run the app under XWayland, where drops work (`WAYLAND_DISPLAY= vectorcraft`).
-- **Pens and pen displays under Wayland (#491):** winit 0.30 doesn't bind the Wayland tablet protocol (`zwp_tablet_v2`; tablet input arrives in winit 0.31, [winit#4318](https://github.com/rust-windowing/winit/pull/4318), [egui#7731](https://github.com/emilk/egui/pull/7731)). Since Plasma 6.3, KWin no longer turns tablet input into pointer input for such apps ([kwin!6336](https://invent.kde.org/plasma/kwin/-/merge_requests/6336)): the pen moves the compositor's cursor over the window, but the app gets no motion or presses and shows none of its own cursors. Until eframe moves to winit 0.31, either run the app under XWayland, which supports the tablet protocol and hands the pen to X11 apps as a pointer (`WAYLAND_DISPLAY= vectorcraft`, or `env -u WAYLAND_DISPLAY vectorcraft`; for a desktop launcher, put `env WAYLAND_DISPLAY=` before the command in its `Exec=` line), or turn KWin's deprecated emulation back on for the whole session by setting `KWIN_WAYLAND_EMULATE_TABLET=1` in KWin's environment (for example in a file under `~/.config/environment.d/` or in `/etc/environment`) and logging in again. The pen then works as a mouse, without pressure: winit 0.30 reads pen pressure on Windows only (Windows Ink, which reaches the Liquify tools' Use Pressure Pen). Other compositors that don't emulate a pointer for tablets behave the same way.
+- **Dropping files on the window does not work under Wayland:** winit 0.30, which eframe 0.36 runs on, has no Wayland drag and drop ([winit#1881](https://github.com/rust-windowing/winit/issues/1881), added in winit 0.31; [egui#1563](https://github.com/emilk/egui/issues/1563)), so no `dropped_files` arrive. Until eframe moves to winit 0.31: copy the files in the file manager and paste them, use File › Place or Open, or open the window through XWayland, where drops work: set **Preferences › Performance › Linux Display Server** to **X11 (XWayland)** and restart (#1151), or start the app with `WAYLAND_DISPLAY= vectorcraft`. The preference (`linuxDisplayServer`, read at startup in `apps/vectorcraft/src/main.rs`, shown on Linux only) has winit open the window on X11 (`EventLoopBuilderExtX11::with_x11`) when the session is Wayland, `DISPLAY` is set and the X11 libraries winit loads are installed (`apps/vectorcraft/src/xwayland.rs` reads `ldconfig -p` and the usual library directories); otherwise the window opens on Wayland and the log says why. Unlike clearing `WAYLAND_DISPLAY`, it leaves the clipboard on the compositor's own.
+- **Pens and pen displays under Wayland (#491):** winit 0.30 doesn't bind the Wayland tablet protocol (`zwp_tablet_v2`; tablet input arrives in winit 0.31, [winit#4318](https://github.com/rust-windowing/winit/pull/4318), [egui#7731](https://github.com/emilk/egui/pull/7731)). Since Plasma 6.3, KWin no longer turns tablet input into pointer input for such apps ([kwin!6336](https://invent.kde.org/plasma/kwin/-/merge_requests/6336)): the pen moves the compositor's cursor over the window, but the app gets no motion or presses and shows none of its own cursors. Until eframe moves to winit 0.31, either run the app under XWayland, which supports the tablet protocol and hands the pen to X11 apps as a pointer (Preferences › Performance › Linux Display Server › X11 (XWayland), `WAYLAND_DISPLAY= vectorcraft`, or `env -u WAYLAND_DISPLAY vectorcraft`; for a desktop launcher, put `env WAYLAND_DISPLAY=` before the command in its `Exec=` line), or turn KWin's deprecated emulation back on for the whole session by setting `KWIN_WAYLAND_EMULATE_TABLET=1` in KWin's environment (for example in a file under `~/.config/environment.d/` or in `/etc/environment`) and logging in again. The pen then works as a mouse, without pressure: winit 0.30 reads pen pressure on Windows only (Windows Ink, which reaches the Liquify tools' Use Pressure Pen). Other compositors that don't emulate a pointer for tablets behave the same way.
 
 ## Fonts: craft-fonts (optional build input)