fix: wire the mouse side buttons to back and forward

crates/disktree-app/src/state.rs

@@ -2575,10 +2575,17 @@ impl Disktree {
                     self.toggle_mark(&crumbs, cx);
                 }
             }
-            MouseButton::Navigate(NavigationDirection::Back) => {
+            // Buttons 8 and 9. gpui-pre maps them on X11, Wayland and
+            // Windows; a mouse with no side buttons never sends them, and
+            // then the header `<` / `>` and alt-arrows are the whole story.
+            MouseButton::Navigate(NavigationDirection::Back)
+                if self.screen == Screen::Explore =>
+            {
                 self.go_back(cx);
             }
-            MouseButton::Navigate(NavigationDirection::Forward) => {
+            MouseButton::Navigate(NavigationDirection::Forward)
+                if self.screen == Screen::Explore =>
+            {
                 self.go_forward(cx);
             }
             _ => {}

crates/disktree-app/src/tests.rs

@@ -1322,3 +1322,51 @@ fn back_and_forward_retrace_where_you_have_been(cx: &mut TestAppContext) {
         Vec::<usize>::new()
     );
 }
+
+/// The mouse's back and forward buttons retrace the same history as
+/// alt-arrows and the header buttons, and only on the explore screen.
+#[gpui_kit::test]
+fn mouse_side_buttons_go_back_and_forward(cx: &mut TestAppContext) {
+    use gpui_kit::{Modifiers, MouseButton, NavigationDirection};
+
+    cx.update(gpui_omarchy::init);
+    let temp = fixture();
+    let (view, cx) = view_over(temp.path(), cx);
+    cx.simulate_resize(gpui_kit::size(px(1400.), px(900.)));
+    draw(cx);
+
+    let (junk, deeper) = update(&view, cx, |app, cx| {
+        let junk = child_crumbs(app, &[], "junk");
+        let deeper = child_crumbs(app, &junk, "deeper");
+        app.select(Some(junk.clone()), cx);
+        app.descend(cx);
+        app.select(Some(deeper.clone()), cx);
+        app.descend(cx);
+        (junk, deeper)
+    });
+    draw(cx);
+    assert_eq!(read(&view, cx, |app| app.crumbs.clone()), deeper);
+
+    // Over the mosaic, buttons 8 and 9 step the history, as alt-arrows do.
+    let mosaic = cx.debug_bounds("treemap").expect("the mosaic is drawn");
+    let at = mosaic.center();
+    let press_button = |cx: &mut Window, button: MouseButton| {
+        cx.simulate_mouse_move(at, None, Modifiers::none());
+        cx.simulate_mouse_down(at, button, Modifiers::none());
+        cx.simulate_mouse_up(at, button, Modifiers::none());
+        draw(cx);
+    };
+    press_button(cx, MouseButton::Navigate(NavigationDirection::Back));
+    assert_eq!(read(&view, cx, |app| app.crumbs.clone()), junk);
+    press_button(cx, MouseButton::Navigate(NavigationDirection::Forward));
+    assert_eq!(read(&view, cx, |app| app.crumbs.clone()), deeper);
+
+    // On the review screen the same press changes nothing: the marked list
+    // is not somewhere the history can take you back to.
+    update(&view, cx, |app, cx| app.toggle_mark(&junk, cx));
+    press(cx, "c");
+    assert_eq!(read(&view, cx, |app| app.screen), Screen::Review);
+    press_button(cx, MouseButton::Navigate(NavigationDirection::Back));
+    assert_eq!(read(&view, cx, |app| app.crumbs.clone()), deeper);
+    assert_eq!(read(&view, cx, |app| app.screen), Screen::Review);
+}

crates/disktree-app/src/treemap_view.rs

@@ -14,10 +14,10 @@ use std::rc::Rc;
 use disktree_core::treemap::Rect;
 use gpui_kit::{
     App, Bounds, ContentMask, Context, Corners, Edges, Font, FontWeight, Hsla,
-    InteractiveElement as _, IntoElement, MouseButton, MouseDownEvent,
-    MouseMoveEvent, ParentElement as _, Pixels, Point, ScrollWheelEvent,
-    SharedString, Size, StatefulInteractiveElement as _, Styled, TextAlign,
-    TextRun, Window, canvas, div, pattern_slash, px, quad,
+    InteractiveElement as _, IntoElement, MouseDownEvent, MouseMoveEvent,
+    ParentElement as _, Pixels, Point, ScrollWheelEvent, SharedString, Size,
+    StatefulInteractiveElement as _, Styled, TextAlign, TextRun, Window,
+    canvas, div, pattern_slash, px, quad,
 };
 use gpui_omarchy::{ActiveTheme, Theme};
 
@@ -86,6 +86,7 @@ pub fn mosaic(
 
     div()
         .id("disktree-treemap")
+        .debug_selector(|| "treemap".into())
         .relative()
         .flex_1()
         .min_h_0()
@@ -100,18 +101,13 @@ pub fn mosaic(
         .on_mouse_move(cx.listener(|this, event: &MouseMoveEvent, _, cx| {
             this.on_mouse_move(event, cx);
         }))
-        .on_mouse_down(
-            MouseButton::Left,
-            cx.listener(|this, event: &MouseDownEvent, _, cx| {
-                this.on_mouse_down(event, cx);
-            }),
-        )
-        .on_mouse_down(
-            MouseButton::Middle,
-            cx.listener(|this, event: &MouseDownEvent, _, cx| {
-                this.on_mouse_down(event, cx);
-            }),
-        )
+        // One listener for every button, because the interesting ones are not
+        // the three the platform names: buttons 8 and 9 arrive as
+        // `MouseButton::Navigate`, and a per-button registration would have
+        // to be repeated for each.
+        .on_any_mouse_down(cx.listener(|this, event: &MouseDownEvent, _, cx| {
+            this.on_mouse_down(event, cx);
+        }))
         .on_scroll_wheel(cx.listener(
             |this, event: &ScrollWheelEvent, _, cx| {
                 this.on_scroll_wheel(event, cx);

crates/disktree-app/src/views.rs

@@ -2826,9 +2826,9 @@ fn card_surface(cx: &gpui_kit::App) -> Div {
 /// at the pointer, over the button itself.
 fn history_card(app: &Disktree, back: bool, cx: &gpui_kit::App) -> Div {
     let (label, keys) = if back {
-        ("Back", "alt \u{2190} back")
+        ("Back", "alt \u{2190} \u{00b7} side button")
     } else {
-        ("Forward", "alt \u{2192} forward")
+        ("Forward", "alt \u{2192} \u{00b7} side button")
     };
     let card = app
         .history_target(back)
@@ -3002,7 +3002,7 @@ fn help_overlay(app: &Disktree, cx: &gpui_kit::App) -> Div {
         ("\u{232b} / esc", "Go up one directory"),
         (
             "alt \u{2190} / \u{2192}",
-            "Back or forward through where you have been",
+            "Back or forward, as do the mouse's side buttons",
         ),
         (
             "\u{2190} \u{2191} \u{2193} \u{2192}",