fix(dock): keep an auto-hiding panel out while its colour popup is open

The Layer Manager's colour dropdown draws as an overlay, which the
docked edge's mouse area reads as the pointer leaving. The auto-hide
timer then collapsed the panel and the dropdown with it, so no colour
could be picked. Defer the hide while a pallet colour dropdown or the
Select Color window is open.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014ihuqzxdUhd9UbioPn5MGu

src/app/dock/tests.rs

@@ -393,6 +393,30 @@ fn dock_hover_reveals_groups_only_on_an_auto_hiding_edge() {
     assert!(app.dock_edge_expanded(DockSide::Left));
 }
 
+#[test]
+fn dock_auto_hide_waits_for_an_open_layer_color_dropdown() {
+    use crate::ui::dock::{DockGroup, DockMsg, PanelId};
+    let mut app = dock_app();
+    app.dock.left.push(DockGroup::single(PanelId::Layers));
+    let _ = app.on_dock(DockMsg::AutoCollapseToggle(PanelId::Layers));
+    let _ = app.on_dock(DockMsg::Hover(PanelId::Layers));
+    let _ = app.on_dock(DockMsg::HoverSettled(app.dock_hover_gen));
+    assert_eq!(app.dock_peek, Some(PanelId::Layers));
+    // Opening a row's colour swatch, then moving onto its dropdown, reads
+    // as the pointer leaving the edge: the panel must stay out.
+    let _ = app.update(Message::LayerColorPickerToggle("0".to_string()));
+    assert!(app.tabs[app.active_tab].layers.color_picker_row.is_some());
+    let _ = app.on_dock(DockMsg::HoverExit);
+    let _ = app.on_dock(DockMsg::HoverSettled(app.dock_hover_gen));
+    assert_eq!(app.dock_peek, Some(PanelId::Layers));
+    let _ = app.on_dock(DockMsg::HoverSettled(app.dock_hover_gen));
+    assert_eq!(app.dock_peek, Some(PanelId::Layers));
+    // Once the dropdown closes with the pointer still away, it hides.
+    let _ = app.update(Message::LayerColorPickerToggle("0".to_string()));
+    let _ = app.on_dock(DockMsg::HoverSettled(app.dock_hover_gen));
+    assert_eq!(app.dock_peek, None);
+}
+
 #[test]
 fn dock_float_resize_grows_the_panel() {
     use crate::ui::dock::{DockMsg, FloatPanel, PanelId};