refactor(ui): migrate all push_parent/pop_parent pairs to in_parent closures

269 hand-balanced parent stack mutations across 22 files become closure-
scoped tree.in_parent(entity, |tree| { ... }) calls. The closures are
impossible to mis-balance, eliminate the debug-build cycle panic surface
that bit us earlier, and make the structure of each builder visually
obvious through nesting.

Touches gallery, showcase, editor (top_bar/inspector/tree/materials/
browsers/overlays/status/viewport_controls/detached_window), game
(title/pause/hud/confirm_quit/settings_screen), jukebox panel, mosaic
window_ui, picking, decals, fireworks, navmesh.

Also collapses several Rc<RefCell<Cell<Entity>>> closure-capture
patterns into plain mut bindings, drops dead let _ = var; suppression
lines, and removes the unused TRANSPARENT constant in jukebox theme.

Author: matthewjberger

apps/decals/src/main.rs

@@ -387,30 +387,38 @@ impl DecalsDemo {
                 wrap: false,
             });
         }
-        tree.push_parent(content);
-
-        tree.add_label("Current Decal Type");
-        let type_label = tree.add_label(initial_type_name);
-
-        tree.add_label("Decal Size");
-        let decal_size = tree.add_slider(0.2, 5.0, initial_decal_size);
-
-        let emissive_label = tree.add_label("Emissive Strength");
-        let emissive_strength = tree.add_slider(0.0, 10.0, initial_emissive_strength);
-
-        let show_preview = tree.add_checkbox("Show Preview", initial_show_preview);
-        let use_awesomeface = tree.add_checkbox("Use Awesomeface Texture", initial_use_awesomeface);
-
-        let active_label = tree.add_label("Active Decals: 0");
-        let clear_button = tree.add_button("Clear All Decals");
-
-        tree.add_label("");
-        tree.add_label("Bloom");
-        let bloom_enabled = tree.add_checkbox("Enable Bloom", bloom_enabled_initial);
-        tree.add_label("Intensity");
-        let bloom_intensity = tree.add_slider(0.0, 2.0, bloom_intensity_initial);
-
-        tree.pop_parent();
+        let mut type_label = Entity::default();
+        let mut decal_size = Entity::default();
+        let mut emissive_label = Entity::default();
+        let mut emissive_strength = Entity::default();
+        let mut show_preview = Entity::default();
+        let mut use_awesomeface = Entity::default();
+        let mut active_label = Entity::default();
+        let mut clear_button = Entity::default();
+        let mut bloom_enabled = Entity::default();
+        let mut bloom_intensity = Entity::default();
+        tree.in_parent(content, |tree| {
+            tree.add_label("Current Decal Type");
+            type_label = tree.add_label(initial_type_name);
+
+            tree.add_label("Decal Size");
+            decal_size = tree.add_slider(0.2, 5.0, initial_decal_size);
+
+            emissive_label = tree.add_label("Emissive Strength");
+            emissive_strength = tree.add_slider(0.0, 10.0, initial_emissive_strength);
+
+            show_preview = tree.add_checkbox("Show Preview", initial_show_preview);
+            use_awesomeface = tree.add_checkbox("Use Awesomeface Texture", initial_use_awesomeface);
+
+            active_label = tree.add_label("Active Decals: 0");
+            clear_button = tree.add_button("Clear All Decals");
+
+            tree.add_label("");
+            tree.add_label("Bloom");
+            bloom_enabled = tree.add_checkbox("Enable Bloom", bloom_enabled_initial);
+            tree.add_label("Intensity");
+            bloom_intensity = tree.add_slider(0.0, 2.0, bloom_intensity_initial);
+        });
         tree.finish();
 
         ui_set_visible(world, panel, self.show_controls);

apps/editor/src/systems/retained_ui/browsers.rs

@@ -82,13 +82,14 @@ fn build_khronos(tree: &mut UiTreeBuilder) -> KhronosHandles {
     let panel = tree.add_floating_panel("khronos_browser", "Khronos sample assets", KHRONOS_RECT);
     ui_set_visible(tree.world_mut(), panel, false);
     let content = super::panel_content(tree, panel);
-    tree.push_parent(content);
-
-    let filter_input = tree.add_text_input("Search assets");
-    let status_label = browser_status_label(tree, "Loading index...");
-    let grid_root = browser_grid_root(tree);
-
-    tree.pop_parent();
+    let mut filter_input = Entity::default();
+    let mut status_label = Entity::default();
+    let mut grid_root = Entity::default();
+    tree.in_parent(content, |tree| {
+        filter_input = tree.add_text_input("Search assets");
+        status_label = browser_status_label(tree, "Loading index...");
+        grid_root = browser_grid_root(tree);
+    });
 
     KhronosHandles {
         panel,
@@ -106,9 +107,7 @@ fn browser_grid_root(tree: &mut UiTreeBuilder) -> Entity {
         .flex_grow(1.0)
         .without_pointer_events()
         .entity();
-    tree.push_parent(wrapper);
-    let scroll = tree.add_scroll_area_fill(8.0, 8.0);
-    tree.pop_parent();
+    let scroll = tree.in_parent(wrapper, |tree| tree.add_scroll_area_fill(8.0, 8.0));
     widget::<UiScrollAreaData>(tree.world_mut(), scroll)
         .map(|d| d.content_entity)
         .unwrap_or(scroll)
@@ -118,26 +117,26 @@ fn build_polyhaven(tree: &mut UiTreeBuilder) -> PolyhavenHandles {
     let panel = tree.add_floating_panel("polyhaven_browser", "Polyhaven", POLYHAVEN_RECT);
     ui_set_visible(tree.world_mut(), panel, false);
     let content = super::panel_content(tree, panel);
-    tree.push_parent(content);
-
-    let tab_bar = tree.add_tab_bar(&["HDRIs", "Models"], 0);
-    let filter_input = tree.add_text_input("Search Polyhaven");
-    let status = browser_status_label(tree, "Loading index...");
-
-    let wrapper = tree
-        .add_node()
-        .fill_width()
-        .flex_grow(1.0)
-        .without_pointer_events()
-        .entity();
-    tree.push_parent(wrapper);
-    let scroll = tree.add_scroll_area_fill(4.0, 2.0);
-    tree.pop_parent();
-    let list_root = widget::<UiScrollAreaData>(tree.world_mut(), scroll)
-        .map(|d| d.content_entity)
-        .unwrap_or(scroll);
-
-    tree.pop_parent();
+    let mut tab_bar = Entity::default();
+    let mut filter_input = Entity::default();
+    let mut status = Entity::default();
+    let mut list_root = Entity::default();
+    tree.in_parent(content, |tree| {
+        tab_bar = tree.add_tab_bar(&["HDRIs", "Models"], 0);
+        filter_input = tree.add_text_input("Search Polyhaven");
+        status = browser_status_label(tree, "Loading index...");
+
+        let wrapper = tree
+            .add_node()
+            .fill_width()
+            .flex_grow(1.0)
+            .without_pointer_events()
+            .entity();
+        let scroll = tree.in_parent(wrapper, |tree| tree.add_scroll_area_fill(4.0, 2.0));
+        list_root = widget::<UiScrollAreaData>(tree.world_mut(), scroll)
+            .map(|d| d.content_entity)
+            .unwrap_or(scroll);
+    });
 
     PolyhavenHandles {
         panel,
@@ -154,7 +153,6 @@ fn build_sketchfab(tree: &mut UiTreeBuilder) -> SketchfabHandles {
     let panel = tree.add_floating_panel("sketchfab_browser", "Sketchfab", SKETCHFAB_RECT);
     ui_set_visible(tree.world_mut(), panel, false);
     let content = super::panel_content(tree, panel);
-    tree.push_parent(content);
 
     let theme = tree
         .world_mut()
@@ -166,50 +164,56 @@ fn build_sketchfab(tree: &mut UiTreeBuilder) -> SketchfabHandles {
     let text_color = theme.text_color;
     let dim = vec4(0.7, 0.7, 0.75, 1.0);
 
-    tree.add_node()
-        .size(100.pct(), (18.0).px())
-        .with_text("Sketchfab API token", font * 0.85)
-        .text_left()
-        .with_color::<UiBase>(dim)
-        .without_pointer_events()
-        .entity();
-    let token_input = tree.add_text_input("paste your API token");
-    ui_text_input_set_password(tree.world_mut(), token_input, true);
-
-    let link_color = vec4(0.49, 0.71, 0.96, 1.0);
-    let link_hover = vec4(0.66, 0.84, 1.0, 1.0);
-    let token_link = tree
-        .add_node()
-        .size(100.pct(), (18.0).px())
-        .with_text("Get a token at sketchfab.com/settings/password", font * 0.8)
-        .text_left()
-        .with_color::<UiBase>(link_color)
-        .with_color::<UiHover>(link_hover)
-        .with_interaction()
-        .with_cursor_icon(winit::window::CursorIcon::Pointer)
-        .entity();
-
-    tree.add_node()
-        .size(100.pct(), (18.0).px())
-        .with_text("Model URL", font * 0.85)
-        .text_left()
-        .with_color::<UiBase>(dim)
-        .without_pointer_events()
-        .entity();
-    let url_input = tree.add_text_input("https://sketchfab.com/3d-models/...");
-
-    let fetch_button = tree.add_button("Fetch");
-
-    let status_label = tree
-        .add_node()
-        .size(100.pct(), (18.0).px())
-        .with_text("idle", font * 0.85)
-        .text_left()
-        .with_color::<UiBase>(text_color)
-        .without_pointer_events()
-        .entity();
-
-    tree.pop_parent();
+    let mut token_input = Entity::default();
+    let mut url_input = Entity::default();
+    let mut fetch_button = Entity::default();
+    let mut status_label = Entity::default();
+    let mut token_link = Entity::default();
+
+    tree.in_parent(content, |tree| {
+        tree.add_node()
+            .size(100.pct(), (18.0).px())
+            .with_text("Sketchfab API token", font * 0.85)
+            .text_left()
+            .with_color::<UiBase>(dim)
+            .without_pointer_events()
+            .entity();
+        token_input = tree.add_text_input("paste your API token");
+        ui_text_input_set_password(tree.world_mut(), token_input, true);
+
+        let link_color = vec4(0.49, 0.71, 0.96, 1.0);
+        let link_hover = vec4(0.66, 0.84, 1.0, 1.0);
+        token_link = tree
+            .add_node()
+            .size(100.pct(), (18.0).px())
+            .with_text("Get a token at sketchfab.com/settings/password", font * 0.8)
+            .text_left()
+            .with_color::<UiBase>(link_color)
+            .with_color::<UiHover>(link_hover)
+            .with_interaction()
+            .with_cursor_icon(winit::window::CursorIcon::Pointer)
+            .entity();
+
+        tree.add_node()
+            .size(100.pct(), (18.0).px())
+            .with_text("Model URL", font * 0.85)
+            .text_left()
+            .with_color::<UiBase>(dim)
+            .without_pointer_events()
+            .entity();
+        url_input = tree.add_text_input("https://sketchfab.com/3d-models/...");
+
+        fetch_button = tree.add_button("Fetch");
+
+        status_label = tree
+            .add_node()
+            .size(100.pct(), (18.0).px())
+            .with_text("idle", font * 0.85)
+            .text_left()
+            .with_color::<UiBase>(text_color)
+            .without_pointer_events()
+            .entity();
+    });
 
     SketchfabHandles {
         panel,
@@ -318,33 +322,31 @@ fn build_thumbnail_card(tree: &mut UiTreeBuilder, label_text: &str) -> Thumbnail
         .with_cursor_icon(winit::window::CursorIcon::Pointer)
         .entity();
 
-    tree.push_parent(card);
-
-    let slot = tree
-        .add_node()
-        .size((124.0).px(), (84.0).px())
-        .without_pointer_events()
-        .entity();
-
-    tree.push_parent(slot);
-    let image = tree
-        .add_node()
-        .solid(Ab(vec2(1.0, 1.0)), ScalingMode::Fit, vec2(0.0, 0.0))
-        .with_color::<UiBase>(vec4(1.0, 1.0, 1.0, 1.0))
-        .without_pointer_events()
-        .entity();
-    tree.pop_parent();
-
-    tree.add_node()
-        .size((124.0).px(), (24.0).px())
-        .with_text(label_text, font * 0.75)
-        .text_center()
-        .with_text_overflow(TextOverflow::Clip)
-        .with_color::<UiBase>(text_color)
-        .without_pointer_events()
-        .entity();
+    let mut image = Entity::default();
+    tree.in_parent(card, |tree| {
+        let slot = tree
+            .add_node()
+            .size((124.0).px(), (84.0).px())
+            .without_pointer_events()
+            .entity();
 
-    tree.pop_parent();
+        image = tree.in_parent(slot, |tree| {
+            tree.add_node()
+                .solid(Ab(vec2(1.0, 1.0)), ScalingMode::Fit, vec2(0.0, 0.0))
+                .with_color::<UiBase>(vec4(1.0, 1.0, 1.0, 1.0))
+                .without_pointer_events()
+                .entity()
+        });
+
+        tree.add_node()
+            .size((124.0).px(), (24.0).px())
+            .with_text(label_text, font * 0.75)
+            .text_center()
+            .with_text_overflow(TextOverflow::Clip)
+            .with_color::<UiBase>(text_color)
+            .without_pointer_events()
+            .entity();
+    });
     ThumbnailCard { card, image }
 }
 
@@ -539,12 +541,12 @@ fn update_khronos(viewer_world: &mut ViewerWorld, world: &mut World) {
                 {
                     let mut tree_builder = UiTreeBuilder::from_parent(world, grid_root);
                     let grid = build_card_grid(&mut tree_builder);
-                    tree_builder.push_parent(grid);
-                    for label in &card_labels {
-                        let card = build_thumbnail_card(&mut tree_builder, label);
-                        new_cards.push(card);
-                    }
-                    tree_builder.pop_parent();
+                    tree_builder.in_parent(grid, |tree_builder| {
+                        for label in &card_labels {
+                            let card = build_thumbnail_card(tree_builder, label);
+                            new_cards.push(card);
+                        }
+                    });
                     tree_builder.finish_subtree();
                 }
                 let lookup = &mut viewer_world.resources.ui_handles.browsers.khronos.lookup;

apps/editor/src/systems/retained_ui/detached_window.rs

@@ -101,14 +101,14 @@ pub fn build(world: &mut World, window_index: usize, camera: Entity) -> Detached
         .with_depth(UiDepthMode::Set(15.0))
         .flow(FlowDirection::Horizontal, 0.0, 0.0)
         .entity();
-    tree.push_parent(restore_button);
-    tree.add_node()
-        .fill()
-        .with_icon(lookup.arrow_back, 12.0)
-        .with_color::<UiBase>(ICON_COLOR)
-        .without_pointer_events()
-        .entity();
-    tree.pop_parent();
+    tree.in_parent(restore_button, |tree| {
+        tree.add_node()
+            .fill()
+            .with_icon(lookup.arrow_back, 12.0)
+            .with_color::<UiBase>(ICON_COLOR)
+            .without_pointer_events()
+            .entity();
+    });
 
     let controls = viewport_controls::build(&mut tree, camera);