Shell: a control in a drag region occludes it, so it takes its press on Windows, where gpui answers the hit test with the caption over any Drag hitbox left uncovered: window buttons and title bar slots occlude, and a column header's item row does while staying the scroll container, its title a drag region of its own; the mini window drags by its title alone, keeping its hover

src/shell/title_tests.rs

@@ -3,7 +3,7 @@ use gpui::{
     ParentElement, Point, Render, TestAppContext, Window, div, point, prelude::*, px,
 };
 
-use super::TitleBar;
+use super::{ColumnShell, ShellColumn, TitleBar, WindowControls};
 use crate::theme::{Platform, Theme};
 
 struct Bar {
@@ -71,3 +71,104 @@ fn a_wobbling_press_on_the_bar_moves_the_window(cx: &mut TestAppContext) {
         .expect("drawn controls");
     wobble(point(controls.left() - px(200.0), controls.center().y), cx);
 }
+
+/// Counts presses that reach the box under the controls.
+struct Under {
+    platform: Platform,
+    presses: usize,
+}
+
+impl Render for Under {
+    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let view = cx.entity();
+        div()
+            .id("under")
+            .flex()
+            .items_start()
+            .w_full()
+            .on_mouse_down(MouseButton::Left, move |_, _, cx| {
+                view.update(cx, |under, _| under.presses += 1)
+            })
+            .child(
+                div()
+                    .debug_selector(|| "controls".into())
+                    .child(WindowControls::new("controls").platform(self.platform)),
+            )
+    }
+}
+
+/// Each style's controls hide what lies under them.
+#[gpui::test]
+fn window_controls_occlude_what_lies_under(cx: &mut TestAppContext) {
+    cx.update(Theme::init);
+    for platform in [Platform::Windows, Platform::Mac, Platform::Linux] {
+        let (view, cx) = cx.add_window_view(move |_, _| Under {
+            platform,
+            presses: 0,
+        });
+        cx.run_until_parked();
+        let controls = cx.debug_bounds("controls").expect("drawn controls");
+        cx.simulate_event(MouseDownEvent {
+            button: MouseButton::Left,
+            position: controls.center(),
+            modifiers: Modifiers::none(),
+            click_count: 1,
+            first_mouse: false,
+        });
+        assert_eq!(
+            view.read_with(cx, |under, _| under.presses),
+            0,
+            "{platform:?}"
+        );
+    }
+}
+
+/// Title bar and column header with inert slot items.
+struct Slotted;
+
+impl Render for Slotted {
+    fn render(&mut self, _: &mut Window, _: &mut Context<Self>) -> impl IntoElement {
+        let item = |name: &'static str| div().debug_selector(move || name.into()).size_6();
+        let column = ShellColumn::new("main")
+            .leading(item("shell-lead"))
+            .action(item("shell-act"));
+        div()
+            .size_full()
+            .flex()
+            .flex_col()
+            .child(
+                TitleBar::new("bar")
+                    .platform(Platform::Windows)
+                    .child(item("bar-lead"))
+                    .action(item("bar-act")),
+            )
+            .child(
+                ColumnShell::new("shell")
+                    .platform(Platform::Windows)
+                    .column(column),
+            )
+    }
+}
+
+/// A press on a slot item never moves the window.
+#[gpui::test]
+fn a_wobbling_press_on_a_slot_moves_no_window(cx: &mut TestAppContext) {
+    cx.update(Theme::init);
+    let (_, cx) = cx.add_window_view(|_, _| Slotted);
+    cx.run_until_parked();
+    for name in ["bar-lead", "bar-act", "shell-lead", "shell-act"] {
+        let item = cx.debug_bounds(name).expect("a slot item");
+        wobble(item.center(), cx);
+    }
+}
+
+/// A column's title still moves the window; a move panics.
+#[gpui::test]
+#[should_panic(expected = "not implemented")]
+fn a_wobbling_press_on_a_column_title_moves_the_window(cx: &mut TestAppContext) {
+    cx.update(Theme::init);
+    let (_, cx) = cx.add_window_view(|_, _| Slotted);
+    cx.run_until_parked();
+    let items = cx.debug_bounds("column-shell-items-0").expect("the items");
+    wobble(items.center(), cx);
+}