Fix shared element state across component instances

crates/layout/src/dock.rs

@@ -1016,7 +1016,7 @@ fn render_pane(
                 move |_, _| {
                     tabs.iter()
                         .map(|tab| {
-                            let mut entry = Tab::new(tab.title.clone());
+                            let mut entry = Tab::new(tab.panel.clone(), tab.title.clone());
                             if let Some(role) = tab.icon {
                                 entry = entry.icon(role);
                             }

crates/layout/src/resize_handle.rs

@@ -255,6 +255,14 @@ impl RenderOnce for ResizeHandle {
                                             return;
                                         }
 
+                                        if event.pressed_button != Some(MouseButton::Left) {
+                                            drag.update(cx, |drag, cx| {
+                                                drag.dragging = false;
+                                                cx.notify();
+                                            });
+                                            return;
+                                        }
+
                                         let delta = match axis {
                                             Axis::Horizontal => event.position.x - last.x,
                                             Axis::Vertical => event.position.y - last.y,

crates/layout/tests/resize_handle.rs

@@ -151,6 +151,28 @@ fn moves_without_a_drag_report_nothing() {
     assert!(deltas.borrow().is_empty());
 }
 
+/// The button may be released outside the window, where no MouseUp is
+/// delivered — the drag must end when a move reports no pressed button.
+#[test]
+fn releasing_outside_the_window_ends_the_drag() {
+    let (_cx, deltas, _resets, mut visual) = handle_window(Axis::Horizontal, false);
+    let start = handle_center(&mut visual);
+
+    visual.simulate_mouse_down(start, MouseButton::Left, Modifiers::default());
+    visual.simulate_event(MouseMoveEvent {
+        position: point(start.x + px(30.), start.y),
+        pressed_button: None,
+        modifiers: Modifiers::default(),
+    });
+    visual.simulate_event(MouseMoveEvent {
+        position: point(start.x + px(60.), start.y),
+        pressed_button: None,
+        modifiers: Modifiers::default(),
+    });
+
+    assert!(deltas.borrow().is_empty(), "the drag outlived its button");
+}
+
 #[test]
 fn arrow_keys_move_the_seam_when_focused() {
     let (_cx, deltas, _resets, mut visual) = handle_window(Axis::Horizontal, false);