Save changes prompt: arrow keys pick the button, Enter gives it (#683)

In the save-changes prompt, Left and Right pick a button and Enter gives it.

crates/ui-egui/src/documents.rs

@@ -48,6 +48,8 @@ pub struct Documents {
     pub closing: Option<usize>,
     /// Quitting: the tabs answered so far with Don't Save (`None`: not quitting).
     pub quitting: Option<Vec<usize>>,
+    /// The "save changes?" button the arrow keys have picked; Enter gives it.
+    pub choice: Answer,
 }
 
 impl Documents {
@@ -458,8 +460,9 @@ pub fn layout(n: usize, active: usize, room: f32) -> (usize, usize, f32) {
 }
 
 /// What "save changes?" was answered.
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
 pub enum Answer {
+    #[default]
     Save,
     DontSave,
     Cancel,
@@ -473,6 +476,28 @@ pub fn prompt(app: &mut SolveApp, ctx: &egui::Context) {
     let name = tabs_info(app).get(i).map(|x| x.0.clone()).unwrap_or_default();
     let name_display = if name == "Untitled" { crate::i18n::tr("ui.untitled") } else { &name };
     let mut answer: Option<Answer> = None;
+    // Left and Right move between the buttons (Save is picked first); Enter gives the picked one.
+    let order = [Answer::Save, Answer::DontSave, Answer::Cancel];
+    let (left, right, enter) = ctx.input_mut(|x| {
+        (
+            x.consume_key(egui::Modifiers::NONE, egui::Key::ArrowLeft),
+            x.consume_key(egui::Modifiers::NONE, egui::Key::ArrowRight),
+            x.consume_key(egui::Modifiers::NONE, egui::Key::Enter),
+        )
+    });
+    let at = order.iter().position(|a| *a == app.docs.choice).unwrap_or(0);
+    let at = if left {
+        at.saturating_sub(1)
+    } else if right {
+        (at + 1).min(order.len() - 1)
+    } else {
+        at
+    };
+    let choice = order.get(at).copied().unwrap_or_default();
+    app.docs.choice = choice;
+    if enter {
+        answer = Some(choice);
+    }
     let title = crate::i18n::format("document.save_changes", &[("name", name_display)]);
     crate::frame::window(ctx, title, crate::frame::Width::Normal)
         .id(egui::Id::new("sc_close_prompt"))
@@ -483,13 +508,13 @@ pub fn prompt(app: &mut SolveApp, ctx: &egui::Context) {
             ui.label(crate::i18n::format("document.unsaved_changes", &[("name", name_display)]));
             ui.add_space(8.0);
             ui.horizontal(|ui| {
-                if ui.button(crate::i18n::tr("ui.save")).clicked() {
+                if ui.add(egui::Button::new(crate::i18n::tr("ui.save")).selected(choice == Answer::Save)).clicked() {
                     answer = Some(Answer::Save);
                 }
-                if ui.button(crate::i18n::tr("ui.don_t_save")).clicked() {
+                if ui.add(egui::Button::new(crate::i18n::tr("ui.don_t_save")).selected(choice == Answer::DontSave)).clicked() {
                     answer = Some(Answer::DontSave);
                 }
-                if ui.button(crate::i18n::tr("ui.cancel")).clicked() {
+                if ui.add(egui::Button::new(crate::i18n::tr("ui.cancel")).selected(choice == Answer::Cancel)).clicked() {
                     answer = Some(Answer::Cancel);
                 }
             });
@@ -506,6 +531,7 @@ pub fn prompt(app: &mut SolveApp, ctx: &egui::Context) {
 /// Act on the "save changes?" answer (also the control channel's `ui.documents {answer}`).
 pub fn answer_prompt(app: &mut SolveApp, answer: Answer) {
     let Some(i) = app.docs.closing else { return };
+    app.docs.choice = Answer::Save;
     match answer {
         Answer::Save => {
             switch(app, i);

crates/ui-egui/tests/scenarios/s43_quit_asks_to_save.json

@@ -10,7 +10,17 @@
   {"expect": {"shown": "Don't Save", "quit_requested": false}},
   {"key": "Escape"},
   {"expect": {"not_shown": "Don't Save", "quitting": false, "quit_requested": false}},
+  {"note": "Left and Right pick a button (Save first, stopping at the ends) and Enter gives it."},
   {"call": "app.quit"},
-  {"widget": "Don't Save"},
+  {"key": "ArrowRight"},
+  {"key": "ArrowRight"},
+  {"key": "ArrowRight"},
+  {"key": "Enter"},
+  {"expect": {"not_shown": "Don't Save", "quitting": false, "quit_requested": false, "bodies": 1}},
+  {"call": "app.quit"},
+  {"key": "ArrowRight"},
+  {"key": "ArrowRight"},
+  {"key": "ArrowLeft"},
+  {"key": "Enter"},
   {"expect": {"quit_requested": true}}
 ]