diff --git a/contributors/people.toml b/contributors/people.toml
index 8ba666cc..c685b584 100644
--- a/contributors/people.toml
+++ b/contributors/people.toml
@@ -71,3 +71,6 @@ sync_github_name = true
 [people.Hathor875]
 real_name = "Krzysztof Cieślik"
 sync_github_name = true
+
+[people.jay-tau]
+sync_github_name = true
diff --git a/crates/ui-egui/src/canvas.rs b/crates/ui-egui/src/canvas.rs
index 6438c903..15560090 100644
--- a/crates/ui-egui/src/canvas.rs
+++ b/crates/ui-egui/src/canvas.rs
@@ -1772,7 +1772,8 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) {
         None => {}
     }
     // No dialog, close prompt or palette over the page: only then does page input count.
-    let unobstructed = app.dialog.is_none() && app.close_request.is_none() && !app.palette_open;
+    let unobstructed = !app.modal_open() && !app.palette_open;
+    let view = &mut app.views[index];
     if view.organize {
         organize_grid(view, info, doc.allows_assembly(), doc.dirty, unobstructed, ui, &t);
         return;
@@ -3273,7 +3274,7 @@ fn quick_bar(app: &mut PdfCraftApp, area: Rect, ui: &mut egui::Ui) {
 }
 
 /// The organize toolbar: page operations on the selection (Acrobat's Organize Pages bar).
-fn organize_toolbar(view: &mut DocView, info: &DocInfo, editable: bool, dirty: bool, ui: &mut egui::Ui, t: &Tokens) {
+fn organize_toolbar(view: &mut DocView, info: &DocInfo, editable: bool, dirty: bool, unobstructed: bool, ui: &mut egui::Ui, t: &Tokens) {
     let targets = view.target_pages();
     let n = info.pages.len();
     let (first, last) = (targets.first().copied().unwrap_or(0), targets.last().copied().unwrap_or(0));
@@ -3379,8 +3380,9 @@ fn organize_toolbar(view: &mut DocView, info: &DocInfo, editable: bool, dirty: b
             });
         });
     });
-    // Keys act on the selection unless a text field has focus.
-    if editable && !ui.ctx().egui_wants_keyboard_input() {
+    // Keys act on the selection unless a text field or a dialog has them (Delete under
+    // Preferences deleted the selected pages).
+    if editable && unobstructed && !ui.ctx().egui_wants_keyboard_input() {
         use egui::{Key, Modifiers};
         let (del, esc) = ui.input_mut(|i| {
             (
@@ -3431,16 +3433,16 @@ fn gap_button(ui: &mut egui::Ui, gap: usize, at: Pos2, height: f32, label: Strin
     resp.on_hover_text(label).clicked()
 }
 
-fn organize_grid(view: &mut DocView, info: &DocInfo, editable: bool, dirty: bool, auto_scroll_enabled: bool, ui: &mut egui::Ui, t: &Tokens) {
+fn organize_grid(view: &mut DocView, info: &DocInfo, editable: bool, dirty: bool, unobstructed: bool, ui: &mut egui::Ui, t: &Tokens) {
     let ppp = ui.ctx().pixels_per_point();
     // The page image scales with the zoom; the padding and the page number don't.
     let cell = vec2(146.0 * view.grid_zoom + 44.0, 194.0 * view.grid_zoom + 56.0);
     let anchor = view.grid_anchor.take();
     let mut open_page = None;
-    organize_toolbar(view, info, editable, dirty, ui, t);
+    organize_toolbar(view, info, editable, dirty, unobstructed, ui, t);
     let viewport = ui.available_rect_before_wrap();
     view.viewport_screen = viewport;
-    let auto_delta = if auto_scroll_enabled {
+    let auto_delta = if unobstructed {
         view.auto_scroll.update(ui, viewport, true)
     } else {
         view.auto_scroll.cancel();
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index 039103ec..70e14a8d 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -1194,6 +1194,12 @@ impl PdfCraftApp {
         self.active.and_then(|i| self.views.get(i).map(|v| (i, v.id)))
     }
 
+    /// A dialog or prompt is open over the window: the keyboard is its own, and nothing may act
+    /// on the document underneath it.
+    pub(crate) fn modal_open(&self) -> bool {
+        self.dialog.is_some() || self.close_request.is_some() || self.password_prompt.is_some() || self.pending_link.is_some() || self.updates.open
+    }
+
     /// Enable the UI control channel on `ctx` (opt-in; see [`control`]). Returns a client that
     /// sends requests to this app; [`control::serve`] exposes it on loopback.
     pub fn attach_control(&mut self, ctx: &egui::Context) -> control::ControlClient {
@@ -1769,6 +1775,11 @@ impl PdfCraftApp {
             }
             return;
         }
+        // The other dialogs and prompts are modal too (⌘W closed the file behind Preferences,
+        // #870).
+        if self.modal_open() {
+            return;
+        }
         if let Some(view) = self.active.and_then(|i| self.views.get_mut(i))
             && view.auto_scroll.escape(ctx)
         {
@@ -1958,7 +1969,7 @@ impl eframe::App for PdfCraftApp {
         self.shortcuts(ctx);
         // Scrolling is transient: never resume after changing tabs, opening a modal/palette,
         // or returning to a window that lost focus.
-        let blocked = self.dialog.is_some() || self.close_request.is_some() || self.palette_open || !ctx.input(|i| i.focused);
+        let blocked = self.modal_open() || self.palette_open || !ctx.input(|i| i.focused);
         for (index, view) in self.views.iter_mut().enumerate() {
             if blocked || self.active != Some(index) {
                 view.auto_scroll.cancel();
diff --git a/crates/ui-egui/tests/editing.rs b/crates/ui-egui/tests/editing.rs
index 93c244af..518399f9 100644
--- a/crates/ui-egui/tests/editing.rs
+++ b/crates/ui-egui/tests/editing.rs
@@ -6,7 +6,7 @@ use egui::{Key, Modifiers};
 use egui_kittest::Harness;
 use egui_kittest::kittest::{NodeT, Queryable};
 use pdfcraft_render::{PageRenderer, RenderRequest, RequestKind};
-use pdfcraft_ui_egui::{CloseRequest, PdfCraftApp};
+use pdfcraft_ui_egui::{CloseRequest, Dialog, PdfCraftApp};
 
 /// An `n`-page document with a proper xref table; page `i` shows "Page i+1".
 fn fixture(n: usize) -> Vec<u8> {
@@ -356,6 +356,46 @@ fn the_save_prompt_answers_to_the_keyboard() {
     let _ = std::fs::remove_file(out);
 }
 
+#[test]
+fn keys_leave_the_document_under_a_dialog_alone() {
+    // Issue #870: ⌘W with Preferences open closed the file underneath it, and in the page grid
+    // Delete deleted the selected page. While a dialog is open its keys are its own.
+    let mut h = organize(3);
+    h.get_by_label("Page 2").click();
+    h.run_steps(2);
+    h.get_by_label("Rotate clockwise").click();
+    h.run_steps(3);
+    assert!(h.state_mut().execute("app.preferences"));
+    h.run_steps(3);
+    let shift = Modifiers::COMMAND | Modifiers::SHIFT;
+    for (m, key) in [
+        (Modifiers::COMMAND, Key::W),
+        (shift, Key::W),
+        (Modifiers::COMMAND, Key::Z),
+        (Modifiers::COMMAND, Key::D),
+        (Modifiers::COMMAND, Key::F),
+        (Modifiers::NONE, Key::Delete),
+        (Modifiers::NONE, Key::Backspace),
+    ] {
+        h.key_press_modifiers(m, key);
+        h.run_steps(3);
+        let app = h.state();
+        assert_eq!(app.views.len(), 1, "{m:?}+{key:?} closed the file");
+        assert!(app.close_request.is_none(), "{m:?}+{key:?} asked to close the file");
+        assert!(app.session.get(app.views[0].id).unwrap().can_undo().is_some(), "{m:?}+{key:?} undid the rotation");
+        assert!(app.views[0].find.is_none(), "{m:?}+{key:?} opened Find");
+        assert_eq!(app.dialog, Some(Dialog::Preferences), "{m:?}+{key:?} replaced Preferences");
+    }
+    assert_eq!(page_texts(h.state()), ["Page 1", "Page 2", "Page 3"], "a page was deleted under the dialog");
+    h.key_press(Key::Escape);
+    h.run_steps(3);
+    assert!(h.state().dialog.is_none(), "Escape closes Preferences");
+    assert_eq!(h.state().views[0].target_pages(), [1], "Escape went to the dialog, not the page selection");
+    h.key_press_modifiers(Modifiers::COMMAND, Key::W);
+    h.run_steps(3);
+    assert!(h.state().close_request.is_some(), "with the dialog closed, ⌘W closes the file again");
+}
+
 #[test]
 fn clean_tabs_close_without_asking() {
     let mut h = harness(1, |_| {});