feat(statusbar): scrollable layout tabs + layout-list dropdown (#199)

Keep the right-side status-bar tools from being pushed off the bar when a
drawing has many layouts: the layout tabs now live in a horizontal scrollable
that only takes the space left between the menu and the tools, with ‹ › arrows
(and the mouse wheel) to scroll them.

Repurpose the leftmost hamburger — which previously fired a no-op MENU command
— to open a dropdown listing Model and every layout (scrollable, current
highlighted); picking one switches to it, an outside click dismisses it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/mod.rs

@@ -202,6 +202,8 @@ pub(super) struct OpenCADStudio {
     scale_popup_open: bool,
     /// True while the status-bar customization menu is open.
     statusbar_menu_open: bool,
+    /// True while the leftmost hamburger's Model/layout list dropdown is open.
+    layout_list_open: bool,
     /// True while the drawing-units picker is open.
     units_popup_open: bool,
     /// True while the Isolate pill's action menu is open.
@@ -1011,6 +1013,9 @@ pub enum Message {
     OpenRecent(PathBuf),
     /// Open a URL in the system browser (start-page intro video, links).
     OpenUrl(String),
+    /// Scroll the status-bar layout-tab strip horizontally by `delta` px
+    /// (negative = left). Driven by the ‹ › arrows next to the tabs.
+    ScrollLayoutTabs(f32),
     /// Drop a path from the recent-documents list.
     RecentRemove(PathBuf),
     /// User clicked Cancel on the loading overlay. The parser thread keeps
@@ -1215,6 +1220,10 @@ pub enum Message {
     ToggleScalePopup,
     /// Close the scale picker popup.
     CloseScalePopup,
+    /// Toggle the leftmost hamburger's Model/layout list dropdown.
+    ToggleLayoutList,
+    /// Close the Model/layout list dropdown.
+    CloseLayoutList,
     /// Toggle the status-bar customization menu open/closed.
     ToggleStatusBarMenu,
     /// Close the status-bar customization menu.
@@ -1794,6 +1803,7 @@ impl OpenCADStudio {
             snap_popup_open: false,
             scale_popup_open: false,
             statusbar_menu_open: false,
+            layout_list_open: false,
             units_popup_open: false,
             isolate_popup_open: false,
             selection_filter_popup_open: false,

src/app/update/mod.rs

@@ -213,6 +213,11 @@ impl OpenCADStudio {
                 Task::none()
             }
 
+            Message::ScrollLayoutTabs(dx) => iced::widget::operation::scroll_by(
+                iced::advanced::widget::Id::new(crate::ui::statusbar::LAYOUT_TABS_SCROLL_ID),
+                iced::widget::scrollable::AbsoluteOffset { x: dx, y: 0.0 },
+            ),
+
             Message::OpenRecent(path) => {
                 // Recents are read from disk every save → the path may be
                 // stale. Skip silently if the file no longer exists; the
@@ -1336,6 +1341,14 @@ impl OpenCADStudio {
                 self.scale_popup_open = false;
                 Task::none()
             }
+            Message::ToggleLayoutList => {
+                self.layout_list_open ^= true;
+                Task::none()
+            }
+            Message::CloseLayoutList => {
+                self.layout_list_open = false;
+                Task::none()
+            }
             Message::ToggleStatusBarMenu => {
                 self.statusbar_menu_open ^= true;
                 Task::none()
@@ -1946,7 +1959,10 @@ impl OpenCADStudio {
                 Task::none()
             }
 
-            Message::LayoutSwitch(name) => self.on_layout_switch(name),
+            Message::LayoutSwitch(name) => {
+                self.layout_list_open = false;
+                self.on_layout_switch(name)
+            }
 
             Message::LayoutCreate => self.on_layout_create(),
 

src/app/view/mod.rs

@@ -1222,6 +1222,15 @@ impl OpenCADStudio {
             iced::widget::Space::new().width(0).height(0).into()
         };
 
+        let layout_list_layer: Element<'_, Message> = if self.layout_list_open && !tab.is_start {
+            crate::ui::statusbar::statusbar_menu::layout_list_overlay(
+                &tab.scene.layout_names(),
+                &tab.scene.current_layout,
+            )
+        } else {
+            iced::widget::Space::new().width(0).height(0).into()
+        };
+
         let units_layer: Element<'_, Message> = if self.units_popup_open {
             crate::ui::popup::units_popup::units_popup_overlay(tab.scene.document.header.insertion_units)
         } else {
@@ -1286,6 +1295,7 @@ impl OpenCADStudio {
             snap_layer,
             scale_layer,
             statusbar_menu_layer,
+            layout_list_layer,
             units_layer,
             isolate_layer,
             sel_filter_layer,

src/ui/statusbar/mod.rs

@@ -4,9 +4,18 @@ pub mod statusbar_config;
 pub mod statusbar_menu;
 
 use iced::widget::tooltip::Position as TipPos;
-use iced::widget::{button, column, container, mouse_area, row, text, text_input, tooltip, Row};
+use iced::widget::scrollable::{Direction, Scrollbar};
+use iced::widget::{
+    button, column, container, mouse_area, row, scrollable, text, text_input, tooltip, Row,
+};
 use iced::{Background, Border, Color, Element, Length, Theme};
 
+/// Scrollable id of the status-bar layout-tab strip, so the ‹ › arrows (and
+/// `Message::ScrollLayoutTabs`) can scroll it.
+pub const LAYOUT_TABS_SCROLL_ID: &str = "statusbar-layout-tabs";
+/// How far one ‹ / › arrow click scrolls the layout-tab strip.
+const LAYOUT_TAB_SCROLL_STEP: f32 = 96.0;
+
 /// Widget id of the inline layout-rename text input, so the rename can grab
 /// keyboard focus the moment it opens (issue #86).
 pub const LAYOUT_RENAME_INPUT_ID: &str = "layout_rename_input";
@@ -78,10 +87,19 @@ impl StatusBar {
         // Which pills the user has chosen to show on the bar.
         config: &'a StatusBarConfig,
     ) -> Element<'a, Message> {
+        // Leftmost hamburger: opens a dropdown listing Model + every layout, so
+        // a layout can be picked directly even when the tab strip is scrolled.
         let menu_btn = button(crate::ui::icons::tinted(crate::ui::icons::MENU, 14.0, ICON_COLOR))
-            .on_press(Message::Command("MENU".into()))
+            .on_press(Message::ToggleLayoutList)
-            .style(|_: &Theme, _| button::Style {
+            .style(|_: &Theme, status| button::Style {
-                background: Some(Background::Color(Color::TRANSPARENT)),
+                background: Some(Background::Color(match status {
+                    button::Status::Hovered => PILL_BG,
+                    _ => Color::TRANSPARENT,
+                })),
+                border: Border {
+                    radius: 3.0.into(),
+                    ..Default::default()
+                },
                 ..Default::default()
             })
             .padding([2, 8]);
@@ -236,16 +254,31 @@ impl StatusBar {
         let mut bar = Row::new().align_y(iced::Center).spacing(0);
         bar = bar.push(menu_btn);
         if show_layout_tabs {
+            // The layout tabs live in a horizontal scrollable that takes only
+            // the space left between the menu and the right-side tools, so many
+            // layouts scroll instead of pushing the tools off the bar (#199).
+            // ‹ › arrows scroll it (the mouse wheel works too).
+            let mut tabs_row = Row::new().align_y(iced::Center).spacing(0);
             for name in layouts {
                 let is_active = name == current_layout;
                 let renaming = rename_state
                     .filter(|(orig, _)| *orig == name)
                     .map(|(_, edit)| edit.as_str());
-                bar = bar.push(space_tab(name, is_active, renaming));
+                tabs_row = tabs_row.push(space_tab(name, is_active, renaming));
-            }
-            bar = bar.push(add_btn);
             }
+            tabs_row = tabs_row.push(add_btn);
+
+            let tabs_scroll = scrollable(tabs_row)
+                .direction(Direction::Horizontal(Scrollbar::hidden()))
+                .id(iced::advanced::widget::Id::new(LAYOUT_TABS_SCROLL_ID))
+                .width(Length::Shrink);
+
+            bar = bar.push(scroll_arrow(false));
+            bar = bar.push(container(tabs_scroll).width(Length::Fill));
+            bar = bar.push(scroll_arrow(true));
+        } else {
             bar = bar.push(iced::widget::Space::new().width(Length::Fill));
+        }
         bar = bar.push(right_status);
 
         container(bar)
@@ -271,6 +304,38 @@ fn format_coords(p: glam::Vec3) -> String {
     format!("{:.4}, {:.4}, {:.4}", p.x, p.y, p.z)
 }
 
+// ── Layout-tab scroll arrow ───────────────────────────────────────────────
+
+/// A ‹ / › arrow that scrolls the layout-tab strip. `right` picks the
+/// direction (and step sign).
+fn scroll_arrow<'a>(right: bool) -> Element<'a, Message> {
+    let glyph = if right {
+        crate::ui::icons::arrow_right(9.0, ICON_COLOR)
+    } else {
+        crate::ui::icons::arrow_left(9.0, ICON_COLOR)
+    };
+    let step = if right {
+        LAYOUT_TAB_SCROLL_STEP
+    } else {
+        -LAYOUT_TAB_SCROLL_STEP
+    };
+    button(glyph)
+        .on_press(Message::ScrollLayoutTabs(step))
+        .style(|_: &Theme, status| button::Style {
+            background: Some(Background::Color(match status {
+                button::Status::Hovered => PILL_BG,
+                _ => Color::TRANSPARENT,
+            })),
+            border: Border {
+                radius: 3.0.into(),
+                ..Default::default()
+            },
+            ..Default::default()
+        })
+        .padding([2, 4])
+        .into()
+}
+
 // ── Customization handle ──────────────────────────────────────────────────
 
 fn customize_btn() -> Element<'static, Message> {

src/ui/statusbar/statusbar_menu.rs

@@ -2,7 +2,7 @@
 //! opened from the bar's far-right handle. Rendered as a floating overlay
 //! above the status bar, same pattern as the scale picker.
 
-use iced::widget::{button, column, container, mouse_area, row, text};
+use iced::widget::{button, column, container, mouse_area, row, scrollable, text};
 use iced::{Background, Border, Color, Element, Fill, Length, Padding, Theme};
 
 use crate::app::Message;
@@ -51,6 +51,69 @@ pub fn statusbar_menu_overlay(config: &StatusBarConfig) -> Element<'static, Mess
         .into()
 }
 
+/// Dropdown listing Model + every paper layout, opened from the leftmost
+/// hamburger. Pinned bottom-left just above the status bar; a click selects a
+/// layout (and closes), an outside click just closes.
+pub fn layout_list_overlay<'a>(layouts: &[String], current: &str) -> Element<'a, Message> {
+    let rows: Vec<Element<'a, Message>> = layouts
+        .iter()
+        .map(|name| layout_row(name.clone(), name == current))
+        .collect();
+
+    let panel = container(scrollable(column(rows)))
+        .style(|_: &Theme| container::Style {
+            background: Some(Background::Color(PANEL_BG)),
+            border: Border {
+                color: PANEL_BORDER,
+                width: 1.0,
+                radius: 3.0.into(),
+            },
+            ..Default::default()
+        })
+        .width(Length::Fixed(200.0))
+        .max_height(360.0);
+
+    let positioned = container(panel)
+        .align_left(Fill)
+        .align_bottom(Fill)
+        .padding(Padding {
+            bottom: 27.0,
+            left: 4.0,
+            top: 0.0,
+            right: 0.0,
+        })
+        .width(Fill)
+        .height(Fill);
+
+    mouse_area(positioned)
+        .on_press(Message::CloseLayoutList)
+        .into()
+}
+
+fn layout_row<'a>(name: String, is_current: bool) -> Element<'a, Message> {
+    let lbl = text(name.clone())
+        .size(11)
+        .color(if is_current { LABEL_ON } else { LABEL_OFF });
+    button(row![lbl].align_y(iced::Center))
+        .on_press(Message::LayoutSwitch(name))
+        .style(move |_: &Theme, status| button::Style {
+            background: Some(Background::Color(match (is_current, status) {
+                (_, button::Status::Hovered) => ROW_HOVER,
+                (true, _) => Color {
+                    r: 0.18,
+                    g: 0.26,
+                    b: 0.36,
+                    a: 1.0,
+                },
+                _ => Color::TRANSPARENT,
+            })),
+            ..Default::default()
+        })
+        .width(Fill)
+        .padding([4, 12])
+        .into()
+}
+
 fn menu_row(label: &'static str, checked: bool, msg: Message) -> Element<'static, Message> {
     let check = crate::ui::icons::check_cell(checked, CHECK_COLOR);