UI: AutoComplete for cell values can be turned off, Backspace and Escape drop the proposal (fixes #842)

crates/ui-egui/src/backstage.rs

@@ -824,6 +824,12 @@ fn options(app: &mut SheetApp, ui: &mut Ui) {
         app.run_or_alert("view.formulaBar", json!({"on": formula_bar}));
     }
     ui.add_space(18.0);
+    section(ui, lang, "Options|Editing");
+    let mut autocomplete = app.ui.autocomplete;
+    if ui.checkbox(&mut autocomplete, lang.tr("Enable AutoComplete for cell values")).changed() {
+        app.run_or_alert("options.autoComplete", json!({"on": autocomplete}));
+    }
+    ui.add_space(18.0);
     section(ui, lang, "Options|Save");
     let mut autosave = app.grid.autosave();
     if ui.checkbox(&mut autosave, lang.tr("Save .xlsx workbooks automatically after every change")).changed() {

crates/ui-egui/src/control.rs

@@ -181,6 +181,7 @@ pub fn handle(app: &mut SheetApp, ctx: &egui::Context, method: &str, p: &Json) -
                 ("view.darkMode", "Dark Mode", ""),
                 ("view.theme", "Display Theme", ""),
                 ("view.animations", "Animations", "{on?: bool} (toggles without it) → {on}"),
+                ("options.autoComplete", "Enable AutoComplete for cell values", "{on?: bool} (toggles without it) → {on}"),
                 ("view.interfaceScale", "Interface Size", "{percent: 75–200 | \"auto\"} (100 = auto; clamped)"),
                 ("ui.dialog", "Open Dialog", ""),
                 ("ui.backstage", "File (Backstage view)", "{page?: home|new|open|info|saveAs|print|export|options|close}"),

crates/ui-egui/src/formula_bar.rs

@@ -173,6 +173,10 @@ pub fn editor_widget(app: &mut SheetApp, ui: &mut egui::Ui, id: egui::Id, font:
             let enter = i.consume_key(egui::Modifiers::NONE, Key::Enter) || i.consume_key(egui::Modifiers::SHIFT, Key::Enter);
             let tab = i.consume_key(egui::Modifiers::NONE, Key::Tab) || i.consume_key(egui::Modifiers::SHIFT, Key::Tab);
             let esc = i.consume_key(egui::Modifiers::NONE, Key::Escape);
+            // Backspace takes back the AutoComplete proposal (Excel's selected rest), not a typed character.
+            if ed.completion.is_some() && i.consume_key(egui::Modifiers::NONE, Key::Backspace) {
+                ed.completion = None;
+            }
             (enter, tab, esc, alt_enter, cmd_enter, ctrl_shift_enter, m.shift)
         });
         if alt_enter {
@@ -198,6 +202,8 @@ pub fn editor_widget(app: &mut SheetApp, ui: &mut egui::Ui, id: egui::Id, font:
         if esc {
             if !ed.autocomplete.is_empty() {
                 ed.autocomplete.clear();
+            } else if ed.completion.is_some() {
+                ed.completion = None;
             } else {
                 cancel = true;
             }
@@ -305,7 +311,8 @@ pub fn editor_widget(app: &mut SheetApp, ui: &mut egui::Ui, id: egui::Id, font:
     }
     if resp.changed() {
         ed.completion = None;
-        if !ed.is_formula()
+        if app.ui.autocomplete
+            && !ed.is_formula()
             && ed.caret == ed.text.chars().count()
             && let Some(sh) = app.session.active().and_then(|d| d.wb.sheet(ed.sheet))
         {

crates/ui-egui/src/lib.rs

@@ -57,6 +57,9 @@ pub struct UiState {
     pub status_bar: bool,
     /// Motion in the UI: the selection outline glides to a new selection (View ▸ Animations).
     pub animations: bool,
+    /// Enable AutoComplete for cell values (File ▸ Options ▸ Editing): typed text is completed
+    /// from the one matching entry in the same column.
+    pub autocomplete: bool,
     pub recent: Vec<String>,
     /// One-shot keytip request for a ribbon control: set when a keytip action resolves to
     /// [`keytips::Action::Control`], consumed (and cleared) by the control's render site.
@@ -99,6 +102,7 @@ impl Default for UiState {
             formula_bar_expanded: false,
             status_bar: true,
             animations: true,
+            autocomplete: true,
             recent: vec![],
             keytip_invoke: None,
             language: i18n::Language::En,
@@ -497,6 +501,10 @@ impl SheetApp {
                 self.ui.animations = p.get("on").and_then(Json::as_bool).unwrap_or(!self.ui.animations);
                 Ok(json!({"on": self.ui.animations}))
             }
+            "options.autoComplete" => {
+                self.ui.autocomplete = p.get("on").and_then(Json::as_bool).unwrap_or(!self.ui.autocomplete);
+                Ok(json!({"on": self.ui.autocomplete}))
+            }
             "view.interfaceScale" => {
                 // `{"percent": 125}` or `{"percent": "auto"}`; out-of-range values are clamped.
                 let percent = match p.get("percent") {
@@ -780,7 +788,7 @@ impl SheetApp {
         };
         let mut ed = editor::EditState::new(d.wb.active_sheet, at, text, replace, from_formula_bar);
         ed.locale = locale;
-        if replace && !ed.is_formula() {
+        if replace && self.ui.autocomplete && !ed.is_formula() {
             ed.completion = editor::column_completion(sh, at, &ed.text);
         }
         self.editor = Some(ed);

crates/ui-egui/tests/interaction.rs

@@ -485,6 +485,79 @@ fn column_autocomplete_completes_on_enter() {
     assert_eq!(value(&h, "A5"), Value::from("Ea"));
 }
 
+fn completion(h: &egui_kittest::Harness<'static, SheetApp>) -> (String, Option<String>) {
+    let ed = h.state().editor.as_ref().expect("still editing");
+    (ed.text.clone(), ed.completion.clone())
+}
+
+#[test]
+fn column_autocomplete_backspace_and_escape_drop_only_the_proposal() {
+    let mut s = blank();
+    s.execute("range.setValues", json!({"range": "A1", "values": [["Apple"], ["Banana"]]})).unwrap();
+    s.execute("selection.set", json!({"cell": "A3"})).unwrap();
+    let mut h = harness(s);
+    text(&mut h, "ap");
+    assert_eq!(completion(&h), ("ap".into(), Some("Apple".into())), "\"ple\" is proposed after the caret");
+    key(&mut h, Key::Enter, Modifiers::NONE);
+    assert_eq!(value(&h, "A3"), Value::from("Apple"), "Enter accepts it, with the entry's own case");
+    text(&mut h, "ba");
+    key(&mut h, Key::Tab, Modifiers::NONE);
+    assert_eq!(value(&h, "A4"), Value::from("Banana"), "Tab accepts it too");
+
+    // Backspace removes the proposal, not the typed "a".
+    h.state_mut().run("selection.set", json!({"cell": "A5"})).unwrap();
+    h.run_steps(2);
+    text(&mut h, "ba");
+    key(&mut h, Key::Backspace, Modifiers::NONE);
+    assert_eq!(completion(&h), ("ba".into(), None));
+    key(&mut h, Key::Enter, Modifiers::NONE);
+    assert_eq!(value(&h, "A5"), Value::from("ba"));
+
+    // Escape dismisses the proposal and keeps the edit; a second Escape cancels it.
+    text(&mut h, "ap");
+    key(&mut h, Key::Escape, Modifiers::NONE);
+    assert_eq!(completion(&h), ("ap".into(), None));
+    key(&mut h, Key::Escape, Modifiers::NONE);
+    assert!(h.state().editor.is_none());
+    assert_eq!(value(&h, "A6"), Value::Empty);
+}
+
+#[test]
+fn column_autocomplete_skips_ambiguous_prefixes_and_numbers() {
+    let mut s = blank();
+    s.execute("range.setValues", json!({"range": "A1", "values": [["Apricot"], ["Apple"], ["12 Main St"]]})).unwrap();
+    s.execute("selection.set", json!({"cell": "A4"})).unwrap();
+    let mut h = harness(s);
+    text(&mut h, "ap");
+    assert_eq!(completion(&h), ("ap".into(), None), "Apricot and Apple both match");
+    text(&mut h, "p");
+    assert_eq!(completion(&h), ("app".into(), Some("Apple".into())), "one more letter settles it");
+    h.state_mut().cancel_edit();
+    text(&mut h, "12");
+    assert_eq!(completion(&h), ("12".into(), None), "a number is not completed");
+}
+
+#[test]
+fn column_autocomplete_can_be_turned_off() {
+    assert!(gridcraft_ui_egui::UiState::default().autocomplete);
+    let old: gridcraft_ui_egui::UiState = serde_json::from_str(r#"{"dark": true}"#).unwrap();
+    assert!(old.autocomplete, "a ui.json written before the setting existed keeps it on");
+
+    let mut s = blank();
+    s.execute("range.setValues", json!({"range": "A1", "values": [["North"]]})).unwrap();
+    s.execute("selection.set", json!({"cell": "A2"})).unwrap();
+    let mut h = harness(s);
+    assert_eq!(h.state_mut().run("options.autoComplete", json!({"on": false})), Ok(json!({"on": false})));
+    assert!(h.state().dialog.is_none());
+    text(&mut h, "No");
+    assert_eq!(completion(&h), ("No".into(), None));
+    text(&mut h, "r");
+    assert_eq!(completion(&h), ("Nor".into(), None), "typing on doesn't bring it back");
+    key(&mut h, Key::Enter, Modifiers::NONE);
+    assert_eq!(value(&h, "A2"), Value::from("Nor"));
+    assert_eq!(h.state_mut().run("options.autoComplete", json!({})), Ok(json!({"on": true})), "no parameters: it toggles");
+}
+
 /// An .xlsm carrying a VBA project, saved to bytes.
 fn macro_workbook_bytes() -> Vec<u8> {
     let mut wb = gridcraft_engine::model::Workbook::new();