refactor(style): dedup layers/xref row-button style into ui::style::row_button

Moves the byte-identical zebra/selected cell-button bodies from layers.rs and xref_manager.rs plus the layers header-button body into one shared module. All six call sites now use the shared helpers; toolbar_btn helpers untouched (different semantics). No new tests per owner request (pure move, verified by build plus full suite before test removal).

src/ui/style/mod.rs

@@ -10,6 +10,7 @@ pub mod scale_manager;
 pub mod anno_object_scale;
 pub mod style_manager;
 pub mod common;
+pub mod row_button;
 pub mod form;
 pub mod fusion_theme;
 

src/ui/style/row_button.rs

@@ -0,0 +1,57 @@
+//! Row/header button styles shared by the layers and xref list panels.
+//!
+//! Centralizes the zebra/selected row-button coloring previously duplicated
+//! in `src/ui/window/layers.rs` (`layer_cell_button_style` +
+//! `layer_header_button_style`) and `src/ui/window/xref_manager.rs`
+//! (`row_button_style`). The two cell copies were functionally byte-identical
+//! (Hovered → `background.strong`, selected → `primary.weak`, even →
+//! `background.base`, else → `background.weak`); a single source keeps hover,
+//! selection, and zebra colors consistent across both panels.
+
+use iced::widget::button;
+use iced::{Background, Theme};
+
+/// Cell (row) button style — closure form so both `.style(...)` call sites
+/// (`layers.rs`, `xref_manager.rs`) keep their existing shape.
+pub(crate) fn cell_button_style(
+    selected: bool,
+    index: usize,
+) -> impl Fn(&Theme, button::Status) -> button::Style {
+    move |theme: &Theme, status: button::Status| {
+        let palette = theme.palette();
+        let highlighted = matches!(status, button::Status::Hovered);
+        let pair = if highlighted {
+            palette.background.strong
+        } else if selected {
+            palette.primary.weak
+        } else if index % 2 == 0 {
+            palette.background.base
+        } else {
+            palette.background.weak
+        };
+        button::Style {
+            background: highlighted.then_some(Background::Color(pair.color)),
+            text_color: pair.text,
+            ..Default::default()
+        }
+    }
+}
+
+/// Column-header button style (layers panel).
+pub(crate) fn header_button_style(theme: &Theme, status: button::Status) -> button::Style {
+    let palette = theme.palette();
+    let highlighted = matches!(
+        status,
+        button::Status::Hovered | button::Status::Pressed
+    );
+    let pair = if highlighted {
+        palette.background.strong
+    } else {
+        palette.background.weak
+    };
+    button::Style {
+        background: highlighted.then_some(Background::Color(pair.color)),
+        text_color: pair.text,
+        ..Default::default()
+    }
+}

src/ui/window/layers.rs

@@ -3,6 +3,7 @@
 use crate::app::Message;
 use crate::ui::properties::{lw_options, LinetypeItem, LwItem};
 use crate::ui::style::common::muted_style;
+use crate::ui::style::row_button::{cell_button_style, header_button_style};
 use crate::ui::ROW_H;
 use codec::tables::layer::Layer as DocLayer;
 use codec::tables::Table;
@@ -503,48 +504,6 @@ impl LayerPanel {
 
 // ── Sorting helpers ─────────────────────────────────────────────────────────
 
-fn layer_cell_button_style(
-    theme: &Theme,
-    status: button::Status,
-    is_selected: bool,
-    index: usize,
-) -> button::Style {
-    let palette = theme.palette();
-    let highlighted = matches!(status, button::Status::Hovered);
-    let pair = if highlighted {
-        palette.background.strong
-    } else if is_selected {
-        palette.primary.weak
-    } else if index % 2 == 0 {
-        palette.background.base
-    } else {
-        palette.background.weak
-    };
-    button::Style {
-        background: highlighted.then_some(Background::Color(pair.color)),
-        text_color: pair.text,
-        ..Default::default()
-    }
-}
-
-fn layer_header_button_style(theme: &Theme, status: button::Status) -> button::Style {
-    let palette = theme.palette();
-    let highlighted = matches!(
-        status,
-        button::Status::Hovered | button::Status::Pressed
-    );
-    let pair = if highlighted {
-        palette.background.strong
-    } else {
-        palette.background.weak
-    };
-    button::Style {
-        background: highlighted.then_some(Background::Color(pair.color)),
-        text_color: pair.text,
-        ..Default::default()
-    }
-}
-
 /// Packed RGB key for ordering colours deterministically by hue-ish bytes.
 fn color_sort_key(c: AcadColor) -> u32 {
     let c = iced_color_from_acad(&c);
@@ -573,7 +532,7 @@ fn sortable_header<'a>(
     }
     button(content)
         .on_press(Message::LayerSort(col))
-        .style(layer_header_button_style)
+        .style(header_button_style)
         .padding(Padding {
             top: 0.0,
             bottom: 0.0,
@@ -717,9 +676,7 @@ fn layer_row<'a>(
     let svg_btn = |bytes: &'static [u8], on_press: Message| -> Element<'a, Message> {
         button(crate::ui::icons::semantic(bytes, ICON_SZ))
         .on_press(on_press)
-        .style(move |theme: &Theme, status| {
-            layer_cell_button_style(theme, status, is_selected, index)
-        })
+        .style(cell_button_style(is_selected, index))
         .padding(Padding {
             top: COMBO_PAD_V,
             bottom: COMBO_PAD_V,
@@ -747,9 +704,7 @@ fn layer_row<'a>(
 
     let plot_btn: Element<'_, Message> = button(plot_icon)
         .on_press(Message::LayerTogglePlot(index))
-        .style(move |theme: &Theme, status| {
-            layer_cell_button_style(theme, status, is_selected, index)
-        })
+        .style(cell_button_style(is_selected, index))
         .padding(Padding {
             top: COMBO_PAD_V,
             bottom: COMBO_PAD_V,
@@ -788,9 +743,7 @@ fn layer_row<'a>(
                 .size(FONT_SZ),
         )
         .on_press(Message::LayerRenameStart(index))
-        .style(move |theme: &Theme, status| {
-            layer_cell_button_style(theme, status, is_selected, index)
-        })
+        .style(cell_button_style(is_selected, index))
         .padding(Padding {
             top: COMBO_PAD_V,
             bottom: COMBO_PAD_V,

src/ui/window/xref_manager.rs

@@ -10,6 +10,7 @@ use crate::io::xref::collect_entries_with_prev;
 use crate::io::xref_model::{normalize_lexical, Pathtype, RefKind, RefStatus, RefType, ReferenceEntry};
 use crate::ui::ROW_H;
 use crate::ui::style::common::muted_style;
+use crate::ui::style::row_button::cell_button_style;
 use codec::CadDocument;
 use iced::widget::{button, column, container, mouse_area, row, scrollable, text, tooltip};
 use iced::Padding;
@@ -1259,27 +1260,6 @@ fn format_date(modified: Option<SystemTime>) -> String {
 
 // ── Widget helpers (layers.rs conventions) ────────────────────────────────
 
-fn row_button_style(selected: bool, index: usize) -> impl Fn(&Theme, button::Status) -> button::Style {
-    move |theme: &Theme, status: button::Status| {
-        let palette = theme.palette();
-        let highlighted = matches!(status, button::Status::Hovered);
-        let pair = if highlighted {
-            palette.background.strong
-        } else if selected {
-            palette.primary.weak
-        } else if index % 2 == 0 {
-            palette.background.base
-        } else {
-            palette.background.weak
-        };
-        button::Style {
-            background: highlighted.then_some(Background::Color(pair.color)),
-            text_color: pair.text,
-            ..Default::default()
-        }
-    }
-}
-
 fn toolbar_btn(label: String, msg: Option<Message>, fill: bool) -> Element<'static, Message> {
     let mut b = button(text(label).size(11))
         .style(|theme: &Theme, status| {
@@ -1808,7 +1788,7 @@ fn xref_row<'a>(
         let key = entry.key;
         let arrow = button(crate::ui::icons::themed_arrow_toggle(is_expanded, 10.0))
             .on_press(Message::XrefManagerToggleExpand(key))
-            .style(row_button_style(is_selected, display.index))
+            .style(cell_button_style(is_selected, display.index))
             .padding(Padding {
                 top: 6.0,
                 bottom: 6.0,
@@ -1893,7 +1873,7 @@ fn tree_row(
         let key = entry.key;
         let arrow = button(crate::ui::icons::themed_arrow_toggle(is_expanded, 10.0))
             .on_press(Message::XrefManagerToggleExpand(key))
-            .style(row_button_style(is_selected, display.index))
+            .style(cell_button_style(is_selected, display.index))
             .padding(Padding {
                 top: 6.0,
                 bottom: 6.0,