Fix #592 : file dialogs on Linux no longer stop the window answering

VectorCraft asks for a path where it needs one and goes on with it at once, so its file dialogs ran on the UI thread. Windows and macOS dialogs run the window's events meanwhile; on Linux nothing answered the Wayland compositor's pings while a dialog was open, and Hyprland offered to kill the window as not responding. - ui-egui `picks`: every file dialog (open, save, folder, place) goes through one place. With the host's `start_pick` (desktop Linux) the dialog shows on a thread of its own; what asked (the command, the dialog's OK, a panel's or dialog's button) gives up for now and runs again with the picked path when the dialog answers. Another dialog waits for the open one. - The desktop app passes its window as the dialogs' parent on Linux (the portal can then associate its window, "Unhandled parent window type" before) and Windows; macOS shows them as before. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-09 04:59:05 +07:00
27 changed files with 536 additions and 75 deletions
@@ -4,7 +4,7 @@ VectorCraft is a clean-room, open-source, pure-Rust reimplementation of the Adob

 This file tracks **how far we are and what's left**. Time estimates are wall-clock hours of continuous Claude Opus 5.5 agent work (including builds and the CI gate), given both for **one agent** and for **4–6 parallel agents** on disjoint crates. They are counted from the remaining work (see [Parity estimate](#parity-estimate)), calibrated against measured throughput, and updated as work lands.

-_Last updated: 2026-10-09 (after placed documents (File › Place of a `.vectorcraft` file, linked), M4.14–M4.98, M8.1–M8.20, M14.4–M14.7, the MCP prompts, resource templates, completions and logging, the 2026-10-07 issue fixes, the Layers panel rework and the 2026-10-08 community contributions: Pen and shape-tool modifiers, path editing, Layers, Artboards, Swatches/Brushes and dialogs, Japanese composition and PDF text, Hebrew/Arabic type, interface languages (Spanish among them), the font menu, saved selections, MCP and EPS, the missing-font export warning (#319), open paths in the Shape Builder (#374), PDF/`.ai` import keeping strokes live and hidden and nested layers (#372), per-corner Live Corners (#381), SVG type opening at the size it draws at (#396), the Wayland clipboard with copied-file paste (#398), ruler guides that can be selected, moved and deleted (#414), two batches of Preferences options that were stored but unused (#394), skeleton reads with `document.find` for large documents over MCP (#416) and anchors dragged with Direct Selection snapping to points, segments and smart guides, clipped SVG layers opening as clipping layers (#420), PDF/`.ai` layers read on pages of tens of millions of operators (#419), Document Color Mode putting RGB greys on the black plate on request and converting pattern tiles (#421) and movable dialogs with Offset Path's Joins dropdown (#423) and numeric fields scrubbed by dragging their label (#400), stroke weight presets in the stroke unit (#426), the Appearance panel's Opacity popup (#430), type on a path brackets, flip and Type on a Path Options that keep the type in place (#429), Layers rows dragged with a ghost and dropped on the trash or New Layer (#435), tool flyouts opening on a right or corner press (#436), tool flyouts torn off into floating toolbars (#437), the Shape Builder's erase mode deleting edges too (#439), installed fonts registered outside the font folders and fonts installed while the app runs listed in the font menus (#443), alike circular corners on rectangles that aren't square (#442), tool cursors as OS cursors so the pointer no longer trails over the canvas (#444), artboards copied and pasted with their art (#446), guides dragged out of the rulers snapping to the art's side midpoints and the artboards, artboard guides (#451), the toolbar's double arrow and Window › Toolbars › Double Column switching between one and two columns in any window height (#455), the Smart Guides display options and Snapping Tolerance (#394), Font Size and Leading combo boxes with preset lists in the Character and Properties panels and the Control bar (#458), screenshots pasted from the clipboard on macOS, Windows and the web (#457), the Properties panel's Fill and Stroke matching the Control bar's, Illustrator's Window menu panel keys (Shift+F7 for Align…) and Alt-wheel zoom whatever the wheel preference (Discord feedback), the point/area type widget (Discord feedback), groups in legacy Illustrator .ai files (Discord feedback), a rotating desktop log file (#465), image controls in the Control bar and Properties panel: Image Trace with its presets, Mask, Crop Image, Embed/Unembed, and an Image Trace object's preset, Expand and Release (Discord feedback), the Pen working as the Anchor Point tool with Alt held over a selected path's handles and anchors, and anchor buttons that convert, connect and cut paths at the selected anchors (Discord feedback), Japanese hanging punctuation (burasagari, #463), Escape leaving Presentation Mode with no screen mode saved across restarts, documents dropped on the desktop app opening as tabs of their own and a note that an `.ai` file's art off its artboards isn't in the part read (#472), Add/Delete Anchor Point tool icons drawn from the Pen tool's (#479), EPS import running more of PostScript Level 3 (patterns, Type 3 fonts, mesh shadings, masked images, VM and resource probes), and a preview that stands in saying why (Discord feedback, #466, #469, #474), chords with modifiers recorded in Edit › Keyboard Shortcuts (#487), Type Object Selection by Path Only (#394), Anti-aliased Artwork (#394), Show Pixel Grid (#394), pen and touch taps pressed and lifted within one frame clicking where they tapped and the Linux/Wayland pen-tablet workaround (#491), bounding-box resizes landing on the other objects' anchors and centres with labels, and the Rotate, Scale, Shear and Reflect tools snapping their drags (#482), Shift-drag marquees that toggle the objects or anchors they reach and a Lasso whose Alt subtraction keeps the rest of the selection (#483), the mouse wheel stepping the focused numeric field, the dialogs' and preferences' drag values made such fields (#485), Show The Home Screen When No Documents Are Open (#394), Numbers Without Units Are Points (#394), Auto-Collapse Iconic Panels (#394), the Contextual Task Bar moved by its handle and its More Options menu pinning and resetting its position, a designed macOS DMG windoLine truncated
+_Last updated: 2026-10-09 (after placed documents (File › Place of a `.vectorcraft` file, linked), M4.14–M4.98, M8.1–M8.20, M14.4–M14.7, the MCP prompts, resource templates, completions and logging, the 2026-10-07 issue fixes, the Layers panel rework and the 2026-10-08 community contributions: Pen and shape-tool modifiers, path editing, Layers, Artboards, Swatches/Brushes and dialogs, Japanese composition and PDF text, Hebrew/Arabic type, interface languages (Spanish among them), the font menu, saved selections, MCP and EPS, the missing-font export warning (#319), open paths in the Shape Builder (#374), PDF/`.ai` import keeping strokes live and hidden and nested layers (#372), per-corner Live Corners (#381), SVG type opening at the size it draws at (#396), the Wayland clipboard with copied-file paste (#398), ruler guides that can be selected, moved and deleted (#414), two batches of Preferences options that were stored but unused (#394), skeleton reads with `document.find` for large documents over MCP (#416) and anchors dragged with Direct Selection snapping to points, segments and smart guides, clipped SVG layers opening as clipping layers (#420), PDF/`.ai` layers read on pages of tens of millions of operators (#419), Document Color Mode putting RGB greys on the black plate on request and converting pattern tiles (#421) and movable dialogs with Offset Path's Joins dropdown (#423) and numeric fields scrubbed by dragging their label (#400), stroke weight presets in the stroke unit (#426), the Appearance panel's Opacity popup (#430), type on a path brackets, flip and Type on a Path Options that keep the type in place (#429), Layers rows dragged with a ghost and dropped on the trash or New Layer (#435), tool flyouts opening on a right or corner press (#436), tool flyouts torn off into floating toolbars (#437), the Shape Builder's erase mode deleting edges too (#439), installed fonts registered outside the font folders and fonts installed while the app runs listed in the font menus (#443), alike circular corners on rectangles that aren't square (#442), tool cursors as OS cursors so the pointer no longer trails over the canvas (#444), artboards copied and pasted with their art (#446), guides dragged out of the rulers snapping to the art's side midpoints and the artboards, artboard guides (#451), the toolbar's double arrow and Window › Toolbars › Double Column switching between one and two columns in any window height (#455), the Smart Guides display options and Snapping Tolerance (#394), Font Size and Leading combo boxes with preset lists in the Character and Properties panels and the Control bar (#458), screenshots pasted from the clipboard on macOS, Windows and the web (#457), the Properties panel's Fill and Stroke matching the Control bar's, Illustrator's Window menu panel keys (Shift+F7 for Align…) and Alt-wheel zoom whatever the wheel preference (Discord feedback), the point/area type widget (Discord feedback), groups in legacy Illustrator .ai files (Discord feedback), a rotating desktop log file (#465), image controls in the Control bar and Properties panel: Image Trace with its presets, Mask, Crop Image, Embed/Unembed, and an Image Trace object's preset, Expand and Release (Discord feedback), the Pen working as the Anchor Point tool with Alt held over a selected path's handles and anchors, and anchor buttons that convert, connect and cut paths at the selected anchors (Discord feedback), Japanese hanging punctuation (burasagari, #463), Escape leaving Presentation Mode with no screen mode saved across restarts, documents dropped on the desktop app opening as tabs of their own and a note that an `.ai` file's art off its artboards isn't in the part read (#472), Add/Delete Anchor Point tool icons drawn from the Pen tool's (#479), EPS import running more of PostScript Level 3 (patterns, Type 3 fonts, mesh shadings, masked images, VM and resource probes), and a preview that stands in saying why (Discord feedback, #466, #469, #474), chords with modifiers recorded in Edit › Keyboard Shortcuts (#487), Type Object Selection by Path Only (#394), Anti-aliased Artwork (#394), Show Pixel Grid (#394), pen and touch taps pressed and lifted within one frame clicking where they tapped and the Linux/Wayland pen-tablet workaround (#491), bounding-box resizes landing on the other objects' anchors and centres with labels, and the Rotate, Scale, Shear and Reflect tools snapping their drags (#482), Shift-drag marquees that toggle the objects or anchors they reach and a Lasso whose Alt subtraction keeps the rest of the selection (#483), the mouse wheel stepping the focused numeric field, the dialogs' and preferences' drag values made such fields (#485), Show The Home Screen When No Documents Are Open (#394), Numbers Without Units Are Points (#394), Auto-Collapse Iconic Panels (#394), the Contextual Task Bar moved by its handle and its More Options menu pinning and resetting its position, a designed macOS DMG windoLine truncated

 ## Where we are

@@ -34,6 +34,7 @@ mod window;
 use vectorcraft_engine::Session;
 use vectorcraft_engine::cmd::fileio;
 use vectorcraft_ui_egui::graphics::GraphicsLoss;
+use vectorcraft_ui_egui::picks::PickRequest;
 use vectorcraft_ui_egui::{ClipboardProbeFactory, FilePick, Services, VectorcraftApp};

 struct App {
@@ -185,9 +186,22 @@ fn save_prefs(app: &VectorcraftApp) {
    }
 }

-/// A native file dialog showing `pick`'s file types, folder and suggested name.
-fn file_dialog(pick: &FilePick) -> rfd::FileDialog {
-    let d = pick.filters.iter().fold(rfd::FileDialog::new(), |d, (name, exts)| d.add_filter(*name, exts));
+/// The window file dialogs belong to.
+type Parent = Option<std::sync::Arc<winit::window::Window>>;
+
+/// A native file dialog for `request` over `parent` (Windows and Linux, where the portal then
+/// shows it over the window and keeps it in front; macOS shows them as before).
+fn file_dialog(request: &PickRequest, parent: &Parent) -> rfd::FileDialog {
+    let d = match parent {
+        Some(w) if !cfg!(target_os = "macos") => rfd::FileDialog::new().set_parent(&**w),
+        _ => rfd::FileDialog::new(),
+    };
+    let pick = match request {
+        PickRequest::Open(pick) | PickRequest::Save(pick) => pick,
+        PickRequest::OpenMany => return fileio::place_filters().fold(d.set_title("Place"), |d, (name, exts)| d.add_filter(name, exts)),
+        PickRequest::Folder => return d,
+    };
+    let d = pick.filters.iter().fold(d, |d, (name, exts)| d.add_filter(*name, exts));
    let d = match &pick.folder {
        Some(folder) => d.set_directory(folder),
        None => d,
@@ -195,6 +209,28 @@ fn file_dialog(pick: &FilePick) -> rfd::FileDialog {
    if pick.name.is_empty() { d } else { d.set_file_name(&pick.name) }
 }

+/// Show `dialog` for `request` (on the calling thread, until it closes) → the paths picked.
+fn show_dialog(dialog: rfd::FileDialog, request: &PickRequest) -> Vec<String> {
+    let paths = match request {
+        PickRequest::Open(_) => dialog.pick_file().into_iter().collect(),
+        PickRequest::OpenMany => dialog.pick_files().unwrap_or_default(),
+        PickRequest::Save(pick) => {
+            // The Templates folder may not exist yet.
+            if let Some(folder) = &pick.folder {
+                let _ = std::fs::create_dir_all(folder);
+            }
+            dialog.save_file().into_iter().collect()
+        }
+        PickRequest::Folder => dialog.pick_folder().into_iter().collect(),
+    };
+    paths.into_iter().map(|p| p.to_string_lossy().to_string()).collect()
+}
+
+/// Show the dialog for `request` over `parent` now → the paths picked.
+fn pick_now(request: PickRequest, parent: &Parent) -> Vec<String> {
+    show_dialog(file_dialog(&request, parent), &request)
+}
+
 /// File → Show in Folder: select `path` in Finder / Explorer, or open its folder elsewhere.
 fn reveal(path: &str) -> Result<(), String> {
    reveal_command(path).spawn().map(|_| ()).map_err(|e| format!("can't show {path}: {e}"))
@@ -230,25 +266,31 @@ fn write_file(path: &str, bytes: &[u8]) -> Result<(), String> {
    fileio::write_atomic(std::path::Path::new(path), bytes).map_err(|e| e.to_string())
 }

-fn services() -> Services {
+/// Linux: show the dialog for `request` over `parent` on a thread of its own, answering on the
+/// receiver. Shown on the UI thread, nothing would answer the compositor meanwhile, which then
+/// offers to kill the window as not responding (#592).
+fn start_pick(request: PickRequest, parent: &Parent) -> Option<std::sync::mpsc::Receiver<Vec<String>>> {
+    let dialog = file_dialog(&request, parent);
+    let (tx, rx) = std::sync::mpsc::channel();
+    std::thread::Builder::new()
+        .name("file-dialog".into())
+        .spawn(move || {
+            // The app gone meanwhile has no use for the answer.
+            let _ = tx.send(show_dialog(dialog, &request));
+        })
+        .ok()?;
+    Some(rx)
+}
+
+fn services(parent: Parent) -> Services {
+    let (p1, p2, p3, p4, p5) = (parent.clone(), parent.clone(), parent.clone(), parent.clone(), parent);
    Services {
-        pick_open: Some(Box::new(|pick: &FilePick| file_dialog(pick).pick_file().map(|p| p.to_string_lossy().to_string()))),
-        pick_open_multi: Some(Box::new(|| {
-            fileio::place_filters()
-                .fold(rfd::FileDialog::new().set_title("Place"), |d, (name, exts)| d.add_filter(name, exts))
-                .pick_files()
-                .unwrap_or_default()
-                .into_iter()
-                .map(|p| p.to_string_lossy().to_string())
-                .collect()
-        })),
-        pick_save: Some(Box::new(|pick: &FilePick| {
-            // The Templates folder may not exist yet.
-            if let Some(folder) = &pick.folder {
-                let _ = std::fs::create_dir_all(folder);
-            }
-            file_dialog(pick).save_file().map(|p| p.to_string_lossy().to_string())
-        })),
+        pick_open: Some(Box::new(move |pick: &FilePick| pick_now(PickRequest::Open(pick.clone()), &p1).into_iter().next())),
+        pick_open_multi: Some(Box::new(move || pick_now(PickRequest::OpenMany, &p2))),
+        pick_save: Some(Box::new(move |pick: &FilePick| pick_now(PickRequest::Save(pick.clone()), &p3).into_iter().next())),
+        // Windows and macOS dialogs run the window's events while they are open; Linux's don't.
+        start_pick: cfg!(all(unix, not(target_os = "macos")))
+            .then(|| Box::new(move |request: PickRequest| start_pick(request, &p5)) as vectorcraft_ui_egui::picks::StartPick),
        read: Some(Box::new(|p: &str| std::fs::read(p).map_err(|e| e.to_string()))),
        write: Some(Box::new(write_file)),
        // Background Save and Export write from a worker thread.
@@ -266,7 +308,7 @@ fn services() -> Services {
        reveal: Some(Box::new(reveal)),
        // Links panel: Edit Original; Package: Show Package. Relink to Folder and Package pick folders.
        open_file: Some(Box::new(open_file)),
-        pick_folder: Some(Box::new(|| rfd::FileDialog::new().pick_folder().map(|p| p.to_string_lossy().to_string()))),
+        pick_folder: Some(Box::new(move || pick_now(PickRequest::Folder, &p4).into_iter().next())),
        // File → Print: the system's printers and print queue.
        print: Some(Box::new(printing::SystemPrint)),
        ..Default::default()
@@ -397,7 +439,7 @@ fn main() -> std::process::ExitCode {
            "VectorCraft",
            options,
            Box::new(move |cc| {
-                let mut app = VectorcraftApp::new(Session::new(), services());
+                let mut app = VectorcraftApp::new(Session::new(), services(cc.winit_window().cloned()));
                load_prefs(&mut app, saved);
                // Fit the window to its monitor, or put it back where it was (still hidden).
                if let Some(w) = cc.winit_window() {
@@ -424,11 +424,8 @@ fn destination(app: &mut VectorcraftApp, ui: &mut egui::Ui, d: &mut Dialog) {
        let pick = app.services.pick_folder.is_some();
        ui.horizontal(|ui| {
            form::text(ui, d, "folder", if pick { 300.0 } else { 334.0 });
-            if pick
-                && widgets::icon_button(ui, "folder-open", tl!("Choose a folder"), false, 26.0).clicked()
-                && let Some(f) = app.services.pick_folder.as_mut().and_then(|pick| pick())
-            {
-                d.fields.insert("folder".into(), json!(f));
+            if pick && widgets::icon_button(ui, "folder-open", tl!("Choose a folder"), false, 26.0).clicked() {
+                crate::picks::folder_field(app, d, "folder");
            }
        });
        form::check(ui, d, "openLocation", tl!("Open Location after Export"));
@@ -145,10 +145,17 @@ fn body(app: &mut VectorcraftApp, ui: &mut egui::Ui, d: &mut Dialog) -> bool {
            }
        }
    }
-    if let Some(a) = act
-        && let Err(e) = run(app, d, a, &preset.name)
-    {
-        app.status(e);
+    if let Some(a) = act {
+        let r = if matches!(a, Action::Import) {
+            // Its file dialog, shown off the UI thread, imports into the dialog as it is then.
+            let current = preset.name.clone();
+            crate::picks::in_dialog(app, d, move |app, d| run(app, d, Action::Import, &current))
+        } else {
+            run(app, d, a, &preset.name)
+        };
+        if let Err(e) = r {
+            app.status(e);
+        }
    }
    false
 }
@@ -181,7 +188,7 @@ fn run(app: &mut VectorcraftApp, d: &mut Dialog, act: Action, current: &str) ->
                return Ok(());
            }
            let pick = crate::FilePick { filters: vec![("Flattener presets", PRESET_EXTS)], ..Default::default() };
-            let path = app.services.pick_open.as_mut().and_then(|f| f(&pick)).ok_or("cancelled")?;
+            let path = crate::picks::open(app, &pick).ok_or("cancelled")?;
            let r = app.run("flattener.presets.import", json!({ "path": path }))?;
            if let Some(first) = r["imported"].get(0).and_then(Value::as_str) {
                select(d, first);
@@ -122,7 +122,7 @@ fn confirm(app: &mut VectorcraftApp, d: &Dialog) -> Result<Value, String> {
            p if !p.is_empty() => p,
            _ => {
                let pick = crate::FilePick { filters: vectorcraft_engine::cmd::fileio::place_filters().collect(), ..Default::default() };
-                app.services.pick_open.as_mut().and_then(|f| f(&pick)).ok_or("cancelled")?
+                crate::picks::open(app, &pick).ok_or("cancelled")?
            }
        };
        out = app.run("links.relink", json!({ "ids": current["ids"], "path": path }))?;
@@ -315,7 +315,8 @@ pub fn cancel(app: &mut VectorcraftApp) {
 /// Apply the open dialog (OK).
 pub fn confirm(app: &mut VectorcraftApp) -> DialogResult {
    let Some(d) = app.ui.dialog.clone() else { return Err("no dialog open".into()) };
-    (spec(&d.kind).confirm)(app, &d)
+    // A file dialog it shows off the UI thread confirms the dialog as it is again.
+    crate::picks::as_entry(app, || crate::picks::Entry::Confirm(Box::new(d.clone())), |app| (spec(&d.kind).confirm)(app, &d))
 }

 pub fn show(app: &mut VectorcraftApp, ctx: &egui::Context) {
@@ -70,11 +70,8 @@ fn body(app: &mut VectorcraftApp, ui: &mut egui::Ui, d: &mut Dialog) -> bool {
    if !downloads(app) {
        widgets::label_row(ui, tl!("Location:"), LABEL, |ui| {
            form::text(ui, d, "folder", 230.0);
-            if let Some(pick) = app.services.pick_folder.as_mut()
-                && ui.button(tl!("Choose…")).clicked()
-                && let Some(f) = pick()
-            {
-                d.fields.insert("folder".into(), json!(f));
+            if app.services.pick_folder.is_some() && ui.button(tl!("Choose…")).clicked() {
+                crate::picks::folder_field(app, d, "folder");
            }
        });
        ui.add_space(4.0);
@@ -102,10 +102,17 @@ fn body(app: &mut VectorcraftApp, ui: &mut egui::Ui, d: &mut Dialog) -> bool {
            details(ui, &t, preset, builtin);
        });
    });
-    if let Some(a) = act
-        && let Err(e) = run(app, d, a, &preset.name)
-    {
-        app.status(e);
+    if let Some(a) = act {
+        let r = if matches!(a, Action::Import) {
+            // Its file dialog, shown off the UI thread, imports into the dialog as it is then.
+            let current = preset.name.clone();
+            crate::picks::in_dialog(app, d, move |app, d| run(app, d, Action::Import, &current))
+        } else {
+            run(app, d, a, &preset.name)
+        };
+        if let Err(e) = r {
+            app.status(e);
+        }
    }
    false
 }
@@ -169,7 +176,7 @@ fn run(app: &mut VectorcraftApp, d: &mut Dialog, act: Action, current: &str) ->
                return Ok(());
            }
            let pick = crate::FilePick { filters: vec![("PDF presets", vectorcraft_engine::cmd::pdfcmds::PRESET_EXTS)], ..Default::default() };
-            let path = app.services.pick_open.as_mut().and_then(|f| f(&pick)).ok_or("cancelled")?;
+            let path = crate::picks::open(app, &pick).ok_or("cancelled")?;
            let r = app.run("pdf.preset.import", json!({ "path": path }))?;
            if let Some(first) = r["imported"].get(0).and_then(Value::as_str) {
                select(d, first);
@@ -150,10 +150,17 @@ fn body(app: &mut VectorcraftApp, ui: &mut egui::Ui, d: &mut Dialog) -> bool {
        });
    });
    let name = preset.name.clone();
-    if let Some(a) = act
-        && let Err(e) = run(app, d, a, &name)
-    {
-        app.status(e);
+    if let Some(a) = act {
+        let r = if matches!(a, Action::Import) {
+            // Its file dialog, shown off the UI thread, imports into the dialog as it is then.
+            let current = name.clone();
+            crate::picks::in_dialog(app, d, move |app, d| run(app, d, Action::Import, &current))
+        } else {
+            run(app, d, a, &name)
+        };
+        if let Err(e) = r {
+            app.status(e);
+        }
    }
    false
 }
@@ -187,7 +194,7 @@ pub(super) fn run(app: &mut VectorcraftApp, d: &mut Dialog, act: Action, current
                return Ok(());
            }
            let pick = crate::FilePick { filters: vec![("Perspective grid presets", PRESET_EXTS)], ..Default::default() };
-            let path = app.services.pick_open.as_mut().and_then(|f| f(&pick)).ok_or("cancelled")?;
+            let path = crate::picks::open(app, &pick).ok_or("cancelled")?;
            let r = app.run("perspective.presets.import", json!({ "path": path }))?;
            if let Some(first) = r["imported"].get(0).and_then(Value::as_str) {
                select(d, first);
@@ -111,10 +111,17 @@ fn body(app: &mut VectorcraftApp, ui: &mut egui::Ui, d: &mut Dialog) -> bool {
            }
        });
    });
-    if let Some(a) = act
-        && let Err(e) = run(app, d, a, &name)
-    {
-        app.status(e);
+    if let Some(a) = act {
+        let r = if matches!(a, Action::Import) {
+            // Its file dialog, shown off the UI thread, imports into the dialog as it is then.
+            let current = name.clone();
+            crate::picks::in_dialog(app, d, move |app, d| run(app, d, Action::Import, &current))
+        } else {
+            run(app, d, a, &name)
+        };
+        if let Err(e) = r {
+            app.status(e);
+        }
    }
    false
 }
@@ -149,7 +156,7 @@ pub(super) fn run(app: &mut VectorcraftApp, d: &mut Dialog, act: Action, current
                return Ok(());
            }
            let pick = crate::FilePick { filters: vec![("Print presets", PRESET_EXTS)], ..Default::default() };
-            let path = app.services.pick_open.as_mut().and_then(|f| f(&pick)).ok_or("cancelled")?;
+            let path = crate::picks::open(app, &pick).ok_or("cancelled")?;
            let r = app.run("print.presets.import", json!({ "path": path }))?;
            if let Some(first) = r["imported"].get(0).and_then(Value::as_str) {
                select(d, first);
@@ -634,3 +634,4 @@
 	Clipboard Handling	Práce se schránkou
 	Appearance of Black	Vzhled černé
 	Devices	Zařízení
+	A file dialog is open: choose there first	Je otevřené dialogové okno souboru: nejprve vyberte v něm
@@ -3598,3 +3598,4 @@ axis	Both	Ambos
 	Off: an editable copy of its art, embedded in this document.	Desactivado: una copia editable de su ilustración, incrustada en este documento.
 	Images: link to the file instead of only embedding it.	Imágenes: vincular al archivo en lugar de solo incrustarlo.
 	VectorCraft documents: one locked object, updated when the file changes.	Documentos de VectorCraft: un objeto bloqueado que se actualiza cuando cambia el archivo.
+	A file dialog is open: choose there first	Hay un cuadro de diálogo de archivos abierto: elija primero en él
@@ -3598,3 +3598,4 @@ axis	Both	Entrambi
 	Off: an editable copy of its art, embedded in this document.	Disattivato: una copia modificabile della sua grafica, incorporata in questo documento.
 	Images: link to the file instead of only embedding it.	Immagini: collega il file invece di incorporarlo soltanto.
 	VectorCraft documents: one locked object, updated when the file changes.	Documenti VectorCraft: un unico oggetto bloccato, aggiornato quando il file cambia.
+	A file dialog is open: choose there first	È aperta una finestra di dialogo dei file: scegli prima lì
@@ -3060,3 +3060,4 @@ theme	Appearance	外観
 	Off: an editable copy of its art, embedded in this document.	オフ：アートの編集可能なコピーをこのドキュメントに埋め込みます。
 	Images: link to the file instead of only embedding it.	画像：埋め込むだけでなく、ファイルにリンクします。
 	VectorCraft documents: one locked object, updated when the file changes.	VectorCraft ドキュメント：ロックされた 1 つのオブジェクト。ファイルの変更時に更新されます。
+	A file dialog is open: choose there first	ファイルダイアログが開いています。先にそちらで選択してください
@@ -2648,3 +2648,4 @@
 	Off: an editable copy of its art, embedded in this document.	Desativado: uma cópia editável da arte, incorporada neste documento.
 	Images: link to the file instead of only embedding it.	Imagens: vincular ao arquivo em vez de apenas incorporá-lo.
 	VectorCraft documents: one locked object, updated when the file changes.	Documentos do VectorCraft: um objeto bloqueado, atualizado quando o arquivo muda.
+	A file dialog is open: choose there first	Há uma caixa de diálogo de arquivos aberta: escolha nela primeiro
@@ -3596,3 +3596,4 @@ axis	Both	Оба
 	Off: an editable copy of its art, embedded in this document.	Выкл.: редактируемая копия его рисунка, внедрённая в этот документ.
 	Images: link to the file instead of only embedding it.	Изображения: связывать с файлом вместо простого внедрения.
 	VectorCraft documents: one locked object, updated when the file changes.	Документы VectorCraft: один заблокированный объект, обновляемый при изменении файла.
+	A file dialog is open: choose there first	Открыто окно выбора файла: сначала сделайте выбор в нём
@@ -3315,3 +3315,4 @@ axis	Both	两者
 	Off: an editable copy of its art, embedded in this document.	关闭：将其图稿的可编辑副本嵌入此文档。
 	Images: link to the file instead of only embedding it.	图像：链接到文件，而不只是嵌入。
 	VectorCraft documents: one locked object, updated when the file changes.	VectorCraft 文档：一个锁定对象，文件更改时随之更新。
+	A file dialog is open: choose there first	文件对话框已打开：请先在其中选择
@@ -3090,3 +3090,4 @@ axis	Both	兩者
 	Off: an editable copy of its art, embedded in this document.	關閉：將其圖稿的可編輯副本內嵌在此文件中。
 	Images: link to the file instead of only embedding it.	影像：連結至檔案，而不只是嵌入。
 	VectorCraft documents: one locked object, updated when the file changes.	VectorCraft 文件：單一鎖定物件，檔案變更時隨之更新。
+	A file dialog is open: choose there first	檔案對話方塊已開啟：請先在其中選擇
@@ -72,7 +72,7 @@ pub fn open_document(app: &mut VectorcraftApp, name: &str, bytes: &[u8], path: O

 /// A path from the open dialog, or "cancelled".
 fn pick_open(app: &mut VectorcraftApp, pick: &FilePick) -> Result<String, String> {
-    app.services.pick_open.as_mut().and_then(|f| f(pick)).ok_or_else(|| "cancelled".into())
+    crate::picks::open(app, pick).ok_or_else(|| "cancelled".into())
 }

 /// Object › Plug-ins › Install Plug-in…: installs the `.wasm` at `path`, else a picked one (the
@@ -164,7 +164,7 @@ fn pick_path(app: &mut VectorcraftApp, pick: &FilePick) -> Result<String, String
    if is_web(app) {
        return Ok(pick.name.clone());
    }
-    let picked = app.services.pick_save.as_mut().and_then(|f| f(pick)).ok_or("cancelled")?;
+    let picked = crate::picks::save(app, pick).ok_or("cancelled")?;
    Ok(with_extension(&picked, &fileio::extension(&pick.name), |_| true))
 }

@@ -36,6 +36,7 @@ pub mod menus;
 pub mod native_menu;
 pub mod palette;
 pub mod panels;
+pub mod picks;
 pub mod place;
 pub mod prefs_dialog;
 pub mod print;
@@ -95,6 +96,8 @@ mod tests_pathtype;
 #[cfg(test)]
 mod tests_pdfoutput;
 #[cfg(test)]
+mod tests_picks;
+#[cfg(test)]
 mod tests_place;
 #[cfg(test)]
 mod tests_plugins;
@@ -233,6 +236,10 @@ pub struct Services {
    pub print: Option<Box<dyn print::PrintService>>,
    /// The macOS menu bar, when the desktop app installed one: the in-window menus are hidden then.
    pub native_menu: Option<native_menu::NativeMenu>,
+    /// Show file dialogs off the UI thread (desktop Linux, where a dialog in line holds the window
+    /// and the compositor finds it not answering): what asked runs again with the answer
+    /// ([`picks`]). Without it they are shown in line.
+    pub start_pick: Option<picks::StartPick>,
 }

 /// Cached canvas raster.
@@ -347,6 +354,8 @@ pub struct VectorcraftApp {
    /// The thread that checks the system clipboard for `system_paste` instead
    /// ([`Services::clipboard_probe`]).
    clipboard_probe: Option<clipboard_probe::Probe>,
+    /// File dialogs shown off the UI thread and what runs again with their answers.
+    pub(crate) picks: picks::Picks,
    /// The look for fonts installed or removed while the app was in the background, running
    /// ([`Self::refresh_installed_fonts`]): whether they were.
    font_check: Option<std::sync::mpsc::Receiver<bool>>,
@@ -426,6 +435,7 @@ impl VectorcraftApp {
            system_paste: false,
            system_paste_at: f64::NEG_INFINITY,
            clipboard_probe: None,
+            picks: picks::Picks::default(),
            font_check: None,
            paste_chord: Default::default(),
            background: Default::default(),
@@ -489,6 +499,16 @@ impl VectorcraftApp {

    /// Run a UI or engine command by id. The single entry point for every frontend path.
    pub fn run(&mut self, id: &str, params: Value) -> Result<Value, String> {
+        // A file dialog it shows off the UI thread runs it again with the path picked.
+        if self.picks.is_entry_free() {
+            let entry = picks::Entry::Command(id.to_string(), params.clone());
+            return picks::as_entry(self, move || entry, |app| app.run_now(id, params));
+        }
+        self.run_now(id, params)
+    }
+
+    /// [`Self::run`] it, inside what asks for file dialogs.
+    fn run_now(&mut self, id: &str, params: Value) -> Result<Value, String> {
        self.run_count = self.run_count.wrapping_add(1);
        if let Some(r) = menus::run_ui_command(self, id, &params) {
            return r;
@@ -790,6 +810,7 @@ impl VectorcraftApp {
            self.system_paste = wanted && self.system_clipboard_pasteable();
        }
        self.poll_font_check(ctx);
+        picks::poll(self, ctx);
        background::poll(self);
        if !self.background.jobs.is_empty() {
            // Keep the status bar's progress moving and pick the result up when it arrives.
@@ -185,17 +185,23 @@ fn collect(app: &mut VectorcraftApp, ctx: &egui::Context, ids: Option<Vec<NodeId
 /// folder picker: the last folder Export for Screens used, else the Desktop); the web downloads
 /// them, several as one zip.
 fn export(app: &mut VectorcraftApp, ids: Vec<u64>, files_each: usize) {
+    // The folder picked off the UI thread exports them then.
+    crate::picks::button(app, move |app| export_now(app, ids.clone(), files_each));
+}
+
+fn export_now(app: &mut VectorcraftApp, ids: Vec<u64>, files_each: usize) {
    let mut p = json!({ "assets": ids });
    if io::is_web(app) {
        p["zip"] = json!(ids.len() * files_each > 1);
    } else {
        let saved = app.session.active().map(|st| st.doc.export_settings.clone()).unwrap_or_default();
-        let folder = match app.services.pick_folder.as_mut() {
-            Some(pick) => match pick() {
+        let folder = if crate::picks::can(app, &crate::picks::PickRequest::Folder) {
+            match crate::picks::folder(app) {
                Some(f) => f,
                None => return,
-            },
-            None => match saved
+            }
+        } else {
+            match saved
                .get("folder")
                .and_then(Value::as_str)
                .filter(|f| !f.is_empty())
@@ -204,7 +210,7 @@ fn export(app: &mut VectorcraftApp, ids: Vec<u64>, files_each: usize) {
            {
                Some(f) => f,
                None => return app.status("choose a folder to export to".to_string()),
-            },
+            }
        };
        p["folder"] = json!(folder);
        p["openLocation"] = json!(saved.get("openLocation").and_then(Value::as_bool).unwrap_or(true));
@@ -154,7 +154,7 @@ pub(crate) fn pick_library_file(app: &mut VectorcraftApp, path: Option<String>)
    }
    path.or_else(|| {
        let pick = crate::FilePick { filters: vectorcraft_engine::cmd::fileio::open_filters().collect(), ..Default::default() };
-        app.services.pick_open.as_mut().and_then(|f| f(&pick))
+        crate::picks::open(app, &pick)
    })
    .map(Some)
    .ok_or_else(|| "cancelled".into())
@@ -116,15 +116,23 @@ fn report(app: &mut VectorcraftApp, r: Result<Value, String>, done: impl FnOnce(

 /// Relink images `ids` to a picked file.
 pub(crate) fn relink(app: &mut VectorcraftApp, ids: Vec<u64>) {
+    crate::picks::button(app, move |app| relink_picked(app, ids.clone()));
+}
+
+fn relink_picked(app: &mut VectorcraftApp, ids: Vec<u64>) {
    let pick = crate::FilePick { filters: vectorcraft_engine::cmd::fileio::place_filters().collect(), ..Default::default() };
-    let Some(path) = app.services.pick_open.as_mut().and_then(|f| f(&pick)) else { return };
+    let Some(path) = crate::picks::open(app, &pick) else { return };
    let r = app.run("links.relink", json!({ "ids": ids, "path": path }));
    report(app, r, |v| format!("Relinked {} image(s)", v["relinked"].as_array().map_or(0, Vec::len)));
 }

 /// Relink images `ids` (none: every missing one) to the files of their names in a picked folder.
 fn relink_to_folder(app: &mut VectorcraftApp, ids: Vec<u64>) {
-    let Some(folder) = app.services.pick_folder.as_mut().and_then(|f| f()) else { return };
+    crate::picks::button(app, move |app| relink_to_picked_folder(app, ids.clone()));
+}
+
+fn relink_to_picked_folder(app: &mut VectorcraftApp, ids: Vec<u64>) {
+    let Some(folder) = crate::picks::folder(app) else { return };
    let ids = Some(ids).filter(|i| !i.is_empty());
    let r = app.run("links.relink", json!({ "ids": ids, "folder": folder }));
    report(app, r, |v| {
@@ -154,9 +162,12 @@ pub(crate) fn unembed(app: &mut VectorcraftApp, id: u64, name: &str) {
        }
        return;
    }
-    let Some(path) = app.services.pick_save.as_mut().and_then(|f| f(&crate::FilePick::named(name))) else { return };
-    let r = app.run("links.unembed", json!({ "id": id, "path": path }));
-    report(app, r, |v| format!("Unembedded to {}", v["path"].as_str().unwrap_or_default()));
+    let name = name.to_string();
+    crate::picks::button(app, move |app| {
+        let Some(path) = crate::picks::save(app, &crate::FilePick::named(&name)) else { return };
+        let r = app.run("links.unembed", json!({ "id": id, "path": path }));
+        report(app, r, |v| format!("Unembedded to {}", v["path"].as_str().unwrap_or_default()));
+    });
 }

 /// The UI commands `links.editOriginal` (open the linked file in its app) and `links.reveal`
@@ -0,0 +1,237 @@
+//! File dialogs that leave the window running (#592).
+//!
+//! The app asks for a path where it needs one (Open, Save As, Export, Place, Relink, presets…)
+//! and goes on with it at once, so a dialog shown on the UI thread holds the window until it
+//! closes. On Windows and macOS the dialog runs the window's events meanwhile; on Linux nothing
+//! does, so a Wayland compositor finds the window not answering and offers to kill it. There the
+//! host shows dialogs on another thread ([`Services::start_pick`]): asking returns no path for now,
+//! and when the dialog answers, what asked (the command, the dialog's OK, a panel's button: the
+//! *entry*) runs again and gets the picked path at once.
+
+use std::rc::Rc;
+use std::sync::mpsc::{Receiver, TryRecvError};
+
+use serde_json::Value;
+
+use crate::state::Dialog;
+use crate::{FilePick, VectorcraftApp};
+
+/// A file dialog to show.
+#[derive(Clone, Debug, PartialEq)]
+pub enum PickRequest {
+    /// An open dialog for one file.
+    Open(FilePick),
+    /// An open dialog for files to place.
+    OpenMany,
+    /// A save dialog.
+    Save(FilePick),
+    /// A folder picker.
+    Folder,
+}
+
+/// The paths a dialog shown off the UI thread picked (none: cancelled).
+pub type PickAnswer = Vec<String>;
+
+/// Shows a dialog off the UI thread; its answer arrives on the receiver. `None` when it can't, and
+/// the dialog is then shown in line.
+pub type StartPick = Box<dyn FnMut(PickRequest) -> Option<Receiver<PickAnswer>>>;
+
+/// What runs again with the picked path.
+#[derive(Clone)]
+pub(crate) enum Entry {
+    /// A command (`app.run`).
+    Command(String, Value),
+    /// A dialog's OK (`dialogs::confirm`), on the dialog as it was.
+    Confirm(Box<Dialog>),
+    /// A panel's or a dialog's button.
+    Call(Rc<dyn Fn(&mut VectorcraftApp)>),
+}
+
+/// A dialog shown off the UI thread, waiting for its answer.
+struct Waiting {
+    request: PickRequest,
+    answer: Receiver<PickAnswer>,
+    entry: Entry,
+}
+
+/// The app's file dialogs ([`VectorcraftApp`]'s `picks`).
+#[derive(Default)]
+pub(crate) struct Picks {
+    /// What is running now and asks for a path, the outermost one.
+    entry: Option<Entry>,
+    waiting: Option<Waiting>,
+    /// A picked answer for the entry running again: the dialog it asks for gets it.
+    answer: Option<(PickRequest, PickAnswer)>,
+}
+
+impl Picks {
+    /// Nothing asking for file dialogs is running.
+    pub(crate) fn is_entry_free(&self) -> bool {
+        self.entry.is_none()
+    }
+}
+
+/// Run `f` as `entry`: a dialog it asks for off the UI thread runs `entry` again when it
+/// answers. Inside another entry, that one runs again instead.
+pub(crate) fn as_entry<R>(app: &mut VectorcraftApp, entry: impl FnOnce() -> Entry, f: impl FnOnce(&mut VectorcraftApp) -> R) -> R {
+    if app.picks.entry.is_some() {
+        return f(app);
+    }
+    app.picks.entry = Some(entry());
+    let r = f(app);
+    app.picks.entry = None;
+    r
+}
+
+/// [`as_entry`] for a panel's or a dialog's button that `f` handles.
+pub(crate) fn button(app: &mut VectorcraftApp, f: impl Fn(&mut VectorcraftApp) + 'static) {
+    let f = Rc::new(f);
+    let again = f.clone();
+    as_entry(app, move || Entry::Call(again), |app| f(app));
+}
+
+/// A dialog body's action `f` on `d` (the open dialog's copy) that asks for a file dialog: shown
+/// off the UI thread, its answer runs `f` again on the open dialog, when it is still of that kind.
+pub(crate) fn in_dialog(
+    app: &mut VectorcraftApp,
+    d: &mut Dialog,
+    f: impl Fn(&mut VectorcraftApp, &mut Dialog) -> Result<(), String> + 'static,
+) -> Result<(), String> {
+    let f = Rc::new(f);
+    let (again, kind) = (f.clone(), d.kind.clone());
+    let entry = move || {
+        Entry::Call(Rc::new(move |app: &mut VectorcraftApp| {
+            let Some(mut d) = app.ui.dialog.take() else { return };
+            let r = if d.kind == kind { again(app, &mut d) } else { Ok(()) };
+            app.ui.dialog = Some(d);
+            if let Err(e) = r {
+                app.status(e);
+            }
+        }))
+    };
+    as_entry(app, entry, |app| f(app, d))
+}
+
+/// A dialog body's folder button: the folder picked into field `key` of `d` ([`in_dialog`]).
+pub(crate) fn folder_field(app: &mut VectorcraftApp, d: &mut Dialog, key: &'static str) {
+    let r = in_dialog(app, d, move |app, d| {
+        if let Some(f) = folder(app) {
+            d.fields.insert(key.into(), serde_json::json!(f));
+        }
+        Ok(())
+    });
+    // Picking a folder doesn't fail.
+    let _ = r;
+}
+
+/// A path from an open dialog for `pick` (none: cancelled, or shown off the UI thread for now).
+pub(crate) fn open(app: &mut VectorcraftApp, pick: &FilePick) -> Option<String> {
+    ask(app, PickRequest::Open(pick.clone()))?.into_iter().next()
+}
+
+/// A path from a save dialog for `pick`.
+pub(crate) fn save(app: &mut VectorcraftApp, pick: &FilePick) -> Option<String> {
+    ask(app, PickRequest::Save(pick.clone()))?.into_iter().next()
+}
+
+/// A folder from the folder picker.
+pub(crate) fn folder(app: &mut VectorcraftApp) -> Option<String> {
+    ask(app, PickRequest::Folder)?.into_iter().next()
+}
+
+/// Paths from the open dialog for files to place (none: cancelled).
+pub(crate) fn open_many(app: &mut VectorcraftApp) -> Vec<String> {
+    ask(app, PickRequest::OpenMany).unwrap_or_default()
+}
+
+/// Whether the host shows `request`'s kind of dialog at all.
+pub(crate) fn can(app: &VectorcraftApp, request: &PickRequest) -> bool {
+    let s = &app.services;
+    match request {
+        PickRequest::Open(_) => s.pick_open.is_some(),
+        PickRequest::OpenMany => s.pick_open_multi.is_some() || s.pick_open.is_some(),
+        PickRequest::Save(_) => s.pick_save.is_some(),
+        PickRequest::Folder => s.pick_folder.is_some(),
+    }
+}
+
+/// The paths `request`'s dialog picked: the answer kept for it, else shown off the UI thread (no
+/// paths for now), else shown in line.
+fn ask(app: &mut VectorcraftApp, request: PickRequest) -> Option<PickAnswer> {
+    // One for another dialog is dropped: the entry took another way this time.
+    if let Some((asked, answer)) = app.picks.answer.take()
+        && asked == request
+    {
+        return Some(answer);
+    }
+    if !can(app, &request) {
+        return None;
+    }
+    if let (Some(entry), Some(start)) = (app.picks.entry.clone(), app.services.start_pick.as_mut()) {
+        if app.picks.waiting.is_some() {
+            app.status(tl!("A file dialog is open: choose there first"));
+            return None;
+        }
+        if let Some(answer) = start(request.clone()) {
+            app.picks.waiting = Some(Waiting { request, answer, entry });
+            return None;
+        }
+    }
+    let s = &mut app.services;
+    let one = |p: Option<String>| Some(p.into_iter().collect());
+    match &request {
+        PickRequest::Open(pick) => one(s.pick_open.as_mut().and_then(|f| f(pick))),
+        PickRequest::Save(pick) => one(s.pick_save.as_mut().and_then(|f| f(pick))),
+        PickRequest::Folder => one(s.pick_folder.as_mut().and_then(|f| f())),
+        PickRequest::OpenMany => match (s.pick_open_multi.as_mut(), s.pick_open.as_mut()) {
+            (Some(many), _) => Some(many()),
+            (None, Some(f)) => one(f(&FilePick::default())),
+            (None, None) => None,
+        },
+    }
+}
+
+/// Each frame: when the dialog shown off the UI thread answers with paths, run its entry again
+/// with them. While it is open, look again shortly.
+pub(crate) fn poll(app: &mut VectorcraftApp, ctx: &egui::Context) {
+    let Some(w) = &app.picks.waiting else { return };
+    let answer = match w.answer.try_recv() {
+        Ok(answer) => answer,
+        Err(TryRecvError::Empty) => {
+            // What asked gave up for now: no "cancelled" while the dialog is open.
+            if app.ui.status == "cancelled" {
+                app.ui.status.clear();
+            }
+            ctx.request_repaint_after(std::time::Duration::from_millis(100));
+            return;
+        }
+        // The dialog's thread is gone: as cancelled.
+        Err(TryRecvError::Disconnected) => vec![],
+    };
+    let Some(Waiting { request, entry, .. }) = app.picks.waiting.take() else { return };
+    if answer.is_empty() {
+        return;
+    }
+    app.picks.answer = Some((request, answer));
+    rerun(app, entry);
+    // An entry that took another way this time leaves the answer unused.
+    app.picks.answer = None;
+}
+
+/// Run `entry` again.
+fn rerun(app: &mut VectorcraftApp, entry: Entry) {
+    let r = match entry {
+        Entry::Command(id, params) => app.run(&id, params).map(|_| ()),
+        Entry::Confirm(d) => {
+            app.ui.dialog = Some(*d);
+            crate::dialogs::confirm(app).map(|_| ())
+        }
+        Entry::Call(f) => {
+            f(app);
+            Ok(())
+        }
+    };
+    if let Err(e) = r {
+        app.status(e);
+    }
+}
@@ -135,10 +135,10 @@ fn pick(app: &mut VectorcraftApp) -> Result<(), String> {
        f();
        return Ok(());
    }
-    let paths = match (app.services.pick_open_multi.as_mut(), app.services.pick_open.as_mut()) {
-        (Some(f), _) => f(),
-        (None, Some(f)) => f(&crate::FilePick { filters: fileio::place_filters().collect(), ..Default::default() }).into_iter().collect(),
-        (None, None) => vec![],
+    let paths = if app.services.pick_open_multi.is_some() {
+        crate::picks::open_many(app)
+    } else {
+        crate::picks::open(app, &crate::FilePick { filters: fileio::place_filters().collect(), ..Default::default() }).into_iter().collect()
    };
    if paths.is_empty() {
        return Err("cancelled".into());
@@ -458,7 +458,7 @@ pub fn run_command(app: &mut VectorcraftApp, id: &str, p: &Value) -> Option<Resu
        "shortcuts.export" => {
            let v = export_json(&app.ui.shortcut_set, &app.ui.shortcut_overrides);
            let bytes = serde_json::to_vec_pretty(&v).unwrap_or_default();
-            let path = s("path").or_else(|| app.services.pick_save.as_mut().and_then(|f| f(&crate::FilePick::named("VectorCraft Shortcuts.json"))));
+            let path = s("path").or_else(|| crate::picks::save(app, &crate::FilePick::named("VectorCraft Shortcuts.json")));
            match path {
                Some(path) => match app.services.write.as_mut() {
                    Some(w) => w(&path, &bytes).map(|_| json!({"path": path})),
@@ -477,7 +477,7 @@ pub fn run_command(app: &mut VectorcraftApp, id: &str, p: &Value) -> Option<Resu
            let data = if let Some(v) = p.get("data") {
                Ok(v.clone())
            } else {
-                let path = s("path").or_else(|| app.services.pick_open.as_mut().and_then(|f| f(&crate::FilePick::default())));
+                let path = s("path").or_else(|| crate::picks::open(app, &crate::FilePick::default()));
                match (path, app.services.read.as_ref()) {
                    (Some(path), Some(r)) => r(&path).and_then(|b| serde_json::from_slice(&b).map_err(|e| e.to_string())),
                    (None, _) => Err("cancelled".into()),
@@ -0,0 +1,113 @@
+//! File dialogs shown off the UI thread (Linux, #592): what asked runs again with the answer.
+
+use std::cell::RefCell;
+use std::rc::Rc;
+use std::sync::mpsc::{Sender, channel};
+
+use serde_json::json;
+use vectorcraft_engine::Session;
+
+use crate::picks::{self, PickRequest};
+use crate::state::Dialog;
+use crate::{FilePick, Services, VectorcraftApp};
+
+const SVG: &[u8] = br#"<svg xmlns="http://www.w3.org/2000/svg" width="40" height="30"><rect width="10" height="10"/></svg>"#;
+
+/// A dialog asked for, and where its answer goes.
+type Asked = (PickRequest, Sender<Vec<String>>);
+
+/// The dialogs showing.
+#[derive(Clone, Default)]
+struct Shown(Rc<RefCell<Vec<Asked>>>);
+
+impl Shown {
+    fn requests(&self) -> Vec<PickRequest> {
+        self.0.borrow().iter().map(|(r, _)| r.clone()).collect()
+    }
+    /// The last dialog shown answers `paths`.
+    fn answer(&self, paths: &[&str]) {
+        let (_, tx) = self.0.borrow_mut().pop().expect("a dialog is showing");
+        tx.send(paths.iter().map(|p| p.to_string()).collect()).unwrap();
+    }
+}
+
+/// A desktop app whose dialogs show off the UI thread (none in line), reading [`SVG`] from any path
+/// and writing files to `written`.
+fn app() -> (VectorcraftApp, Shown, Rc<RefCell<Vec<String>>>) {
+    let (shown, written) = (Shown::default(), Rc::new(RefCell::new(vec![])));
+    let (s, w) = (shown.clone(), written.clone());
+    let in_line = |_: &FilePick| -> Option<String> { panic!("no dialog on the UI thread") };
+    let services = Services {
+        pick_open: Some(Box::new(in_line)),
+        pick_save: Some(Box::new(in_line)),
+        pick_folder: Some(Box::new(|| panic!("no dialog on the UI thread"))),
+        read: Some(Box::new(|_: &str| Ok(SVG.to_vec()))),
+        write: Some(Box::new(move |path: &str, _: &[u8]| {
+            w.borrow_mut().push(path.to_string());
+            Ok(())
+        })),
+        start_pick: Some(Box::new(move |request: PickRequest| {
+            let (tx, rx) = channel();
+            s.0.borrow_mut().push((request, tx));
+            Some(rx)
+        })),
+        ..Default::default()
+    };
+    (VectorcraftApp::new(Session::new(), services), shown, written)
+}
+
+fn poll(app: &mut VectorcraftApp) {
+    picks::poll(app, &egui::Context::default());
+}
+
+#[test]
+fn file_open_opens_what_its_dialog_picks_when_it_answers() {
+    let (mut app, shown, _) = app();
+    // The dialog shows; File › Open gives up for now, without a "cancelled".
+    assert!(app.run("file.open", json!({})).is_err());
+    assert!(matches!(shown.requests().as_slice(), [PickRequest::Open(_)]));
+    poll(&mut app);
+    assert!(app.session.documents().is_empty() && app.ui.status.is_empty(), "{}", app.ui.status);
+    // Another dialog waits for this one.
+    assert!(app.run("file.open", json!({})).is_err());
+    assert_eq!(shown.requests().len(), 1);
+    assert!(app.ui.status.contains("file dialog is open"), "{}", app.ui.status);
+    shown.answer(&["/art/a.svg"]);
+    poll(&mut app);
+    assert_eq!(app.session.documents().len(), 1);
+    assert_eq!(app.session.active().and_then(|d| d.path.clone()).as_deref(), Some("/art/a.svg"));
+    // Cancelled: nothing happens, and dialogs show again.
+    assert!(app.run("file.open", json!({})).is_err());
+    shown.answer(&[]);
+    poll(&mut app);
+    assert_eq!(app.session.documents().len(), 1);
+    assert!(app.run("file.open", json!({})).is_err());
+    assert_eq!(shown.requests().len(), 1);
+}
+
+#[test]
+fn save_as_goes_on_with_the_path_picked() {
+    let (mut app, shown, written) = app();
+    app.run("file.new", json!({"width": 100, "height": 80})).unwrap();
+    app.run("shape.rectangle", json!({"x": 10, "y": 10, "width": 30, "height": 20})).unwrap();
+    assert!(app.run("file.saveAs", json!({})).is_err());
+    assert!(matches!(shown.requests().as_slice(), [PickRequest::Save(_)]));
+    shown.answer(&["/art/poster.svg"]);
+    poll(&mut app);
+    // SVG Options asks next, and its OK writes the file there.
+    assert_eq!(app.ui.dialog.as_ref().map(|d| d.kind.as_str()), Some("svgOptions"));
+    crate::dialogs::confirm(&mut app).unwrap();
+    assert_eq!(*written.borrow(), ["/art/poster.svg"]);
+}
+
+#[test]
+fn a_dialogs_folder_button_fills_its_field_when_the_picker_answers() {
+    let (mut app, shown, _) = app();
+    let mut d = Dialog::new("exportForScreens", json!({"folder": ""}));
+    app.ui.dialog = Some(d.clone());
+    picks::folder_field(&mut app, &mut d, "folder");
+    assert_eq!(shown.requests(), [PickRequest::Folder]);
+    shown.answer(&["/out"]);
+    poll(&mut app);
+    assert_eq!(app.ui.dialog.as_ref().map(|d| d.str("folder")).as_deref(), Some("/out"));
+}