Cargo.lock

@@ -1829,6 +1829,7 @@ version = "1.0.0"
 dependencies = [
  "anyhow",
  "gpui",
+ "gpui-base",
  "gpui-component",
  "itertools 0.13.0",
  "serde",

Cargo.toml

@@ -21,6 +21,7 @@ reqwest_client = { git = "https://github.com/zed-industries/zed" }
 # `tree-sitter-languages` enables syntax highlighting for the TextView
 # code preview (fenced code blocks are highlighted with tree-sitter).
 gpui-component = { git = "https://github.com/longbridge/gpui-component", features = ["tree-sitter-languages"] }
+gpui-base = { git = "https://github.com/longbridge/gpui-component" }
 
 dock = { path = "crates/dock" }
 

crates/dock/Cargo.toml

@@ -8,6 +8,7 @@ publish.workspace = true
 [dependencies]
 gpui.workspace = true
 gpui-component.workspace = true
+gpui-base.workspace = true
 
 anyhow.workspace = true
 serde.workspace = true

crates/dock/src/lib.rs

@@ -4,6 +4,7 @@ mod panel;
 mod resize_handle;
 mod stack_panel;
 mod state;
+mod tab_bar;
 mod tab_panel;
 mod window_controls;
 
@@ -53,7 +54,7 @@ pub(crate) fn t(key: &'static str) -> &'static str {
 }
 
 /// The fixed height of the tab bar, which doubles as the window title bar.
-pub(crate) const TAB_BAR_HEIGHT: Pixels = px(44.);
+pub const TAB_BAR_HEIGHT: Pixels = px(44.);
 
 /// A host-owned drag item, dragged into the dock by the application.
 #[derive(Clone, Debug)]

crates/dock/src/tab_bar.rs

@@ -0,0 +1,469 @@
+use std::sync::Arc;
+
+use gpui::prelude::FluentBuilder;
+use gpui::{
+    AnyElement, App, AppContext, ElementId, Entity, InteractiveElement as _, IntoElement,
+    ParentElement as _, RenderOnce, ScrollHandle, StatefulInteractiveElement, Styled as _, Window,
+    div, px,
+};
+use gpui_base::{InteractiveElementExt, Tab, Tabs};
+use gpui_component::{ActiveTheme, ElementExt, h_flex};
+
+use super::{AnyDrag, DragPanel, PanelView, TabPanel};
+use crate::TAB_BAR_HEIGHT;
+
+/// The dock's custom tab bar, built on gpui-base's unstyled [`Tab`]/[`Tabs`].
+///
+/// The dock owns the pill presentation; the layout mirrors gpui-component's
+/// `TabBar`: a prefix (dock toggle / tab navigation), a scrollable tab strip
+/// with a trailing drop target, then a suffix (panel toolbar).
+///
+/// Tabs are draggable to move panels between groups and double as drop
+/// targets, so panel-level events are forwarded to the owning [`TabPanel`].
+#[derive(IntoElement)]
+pub(crate) struct TabBar {
+    id: ElementId,
+    panels: Vec<Arc<dyn PanelView>>,
+    active_panel: Option<Arc<dyn PanelView>>,
+    collapsed: bool,
+    draggable: bool,
+    droppable: bool,
+    tab_panel: Entity<TabPanel>,
+    scroll_handle: ScrollHandle,
+    prefix: Option<AnyElement>,
+    suffix: Option<AnyElement>,
+    empty_space: Option<AnyElement>,
+}
+
+impl TabBar {
+    pub(crate) fn new(id: impl Into<ElementId>, tab_panel: Entity<TabPanel>) -> Self {
+        Self {
+            id: id.into(),
+            panels: Vec::new(),
+            active_panel: None,
+            collapsed: false,
+            draggable: false,
+            droppable: false,
+            tab_panel,
+            scroll_handle: ScrollHandle::new(),
+            prefix: None,
+            suffix: None,
+            empty_space: None,
+        }
+    }
+
+    /// The panels to show as tabs, in strip order.
+    pub(crate) fn panels(mut self, panels: Vec<Arc<dyn PanelView>>) -> Self {
+        self.panels = panels;
+        self
+    }
+
+    /// The currently active panel; its tab is rendered as the filled pill.
+    pub(crate) fn active_panel(mut self, active_panel: Option<Arc<dyn PanelView>>) -> Self {
+        self.active_panel = active_panel;
+        self
+    }
+
+    /// Collapsed tab panels render no suffix or trailing drop target, and
+    /// their tabs lose the active style and all interactions.
+    pub(crate) fn collapsed(mut self, collapsed: bool) -> Self {
+        self.collapsed = collapsed;
+        self
+    }
+
+    /// Whether the tabs can start a panel drag.
+    pub(crate) fn draggable(mut self, draggable: bool) -> Self {
+        self.draggable = draggable;
+        self
+    }
+
+    /// Whether the tabs and trailing space accept drops.
+    pub(crate) fn droppable(mut self, droppable: bool) -> Self {
+        self.droppable = droppable;
+        self
+    }
+
+    /// Track the strip's scroll state with the given handle, so callers can
+    /// scroll a tab into view with [`ScrollHandle::scroll_to_item`].
+    pub(crate) fn scroll_handle(mut self, scroll_handle: &ScrollHandle) -> Self {
+        self.scroll_handle = scroll_handle.clone();
+        self
+    }
+
+    /// Element shown before the tab strip.
+    pub(crate) fn prefix(mut self, prefix: impl IntoElement) -> Self {
+        self.prefix = Some(prefix.into_any_element());
+        self
+    }
+
+    /// Element shown after the tab strip.
+    pub(crate) fn suffix(mut self, suffix: impl IntoElement) -> Self {
+        self.suffix = Some(suffix.into_any_element());
+        self
+    }
+
+    /// Replace the trailing empty space (the drop target after the last tab).
+    #[cfg(test)]
+    pub(crate) fn empty_space(mut self, empty_space: impl IntoElement) -> Self {
+        self.empty_space = Some(empty_space.into_any_element());
+        self
+    }
+
+    fn render_tab(
+        &self,
+        ix: usize,
+        panel: Arc<dyn PanelView>,
+        active: bool,
+        window: &mut Window,
+        cx: &mut App,
+    ) -> Tab {
+        // While collapsed, tabs lose the active style and all interactions.
+        let droppable = self.collapsed;
+        let tab_panel = self.tab_panel.clone();
+
+        // The `ix` element id keeps each tab's identity stable across renders.
+        Tab::new(ix)
+            .h_6()
+            .px_3()
+            .text_sm()
+            .whitespace_nowrap()
+            .flex()
+            .items_center()
+            .justify_center()
+            .gap_1()
+            .flex_shrink_0()
+            .overflow_hidden()
+            .rounded(cx.theme().radius)
+            .text_color(cx.theme().foreground)
+            .map(|this| {
+                if let Some(tab_name) = panel.tab_name(cx) {
+                    this.child(tab_name)
+                } else {
+                    this.child(panel.title(window, cx))
+                }
+            })
+            // Pill presentation: the selected tab is the filled pill, the
+            // rest are transparent until hovered.
+            .styles(|styles| {
+                styles.selected(|style| {
+                    style
+                        .text_color(cx.theme().tab_active_foreground)
+                        .bg(cx.theme().tab_active)
+                })
+            })
+            .hover(|this| {
+                if active {
+                    this
+                } else {
+                    this.text_color(cx.theme().secondary_foreground)
+                        .bg(cx.theme().secondary_hover)
+                }
+            })
+            .selected(active)
+            .on_click(move |_, window, cx| {
+                tab_panel.update(cx, |view, cx| view.set_active_ix(ix, window, cx));
+            })
+            .when(!droppable, |this| {
+                this.when(self.draggable, |this| {
+                    this.on_drag(
+                        DragPanel::new(panel.clone(), self.tab_panel.clone()),
+                        |drag, offset, _, cx| {
+                            cx.stop_propagation();
+                            drag.drag_offset.set(offset);
+                            cx.new(|_| drag.clone())
+                        },
+                    )
+                })
+                .when(self.droppable, |this| {
+                    this.drag_over::<DragPanel>(|this, _, _, cx| {
+                        this.rounded_l_none()
+                            .border_l_2()
+                            .border_r_0()
+                            .border_color(cx.theme().drag_border)
+                    })
+                    .on_drop({
+                        let tab_panel = self.tab_panel.clone();
+                        move |drag: &DragPanel, window, cx| {
+                            tab_panel.update(cx, |view, cx| {
+                                view.will_split_placement = None;
+                                view.on_drop(drag, Some(ix), true, window, cx);
+                            });
+                        }
+                    })
+                    .drag_over::<AnyDrag>(|this, _, _, cx| {
+                        this.rounded_l_none()
+                            .border_l_2()
+                            .border_r_0()
+                            .border_color(cx.theme().drag_border)
+                    })
+                    .on_drop({
+                        let tab_panel = self.tab_panel.clone();
+                        move |item: &AnyDrag, _, cx| {
+                            tab_panel.update(cx, |view, cx| {
+                                view.will_split_placement = None;
+                                view.emit_drag_drop(item, None, cx);
+                            });
+                        }
+                    })
+                })
+            })
+    }
+
+    fn render_empty_space(&self) -> AnyElement {
+        let tabs_count = self.panels.len();
+
+        // The strip after the last tab is a drop target for panels and
+        // host-owned drag items. Its left edge (right after the last tab)
+        // marks the start of the title-bar drag overlay.
+        let mut empty = div()
+            .id("tab-bar-empty-space")
+            .h_full()
+            .flex_grow_1()
+            .min_w_16()
+            .on_prepaint({
+                let view = self.tab_panel.clone();
+                move |bounds, _, cx| {
+                    view.update(cx, |this, cx| {
+                        if this.title_bar_strip_bounds != Some(bounds) {
+                            this.title_bar_strip_bounds = Some(bounds);
+                            cx.notify();
+                        }
+                    });
+                }
+            });
+
+        if self.droppable {
+            empty = empty
+                .drag_over::<DragPanel>(|this, _, _, cx| this.bg(cx.theme().tokens.drop_target))
+                .on_drop({
+                    let view = self.tab_panel.clone();
+                    move |drag: &DragPanel, window, cx| {
+                        view.update(cx, |this, cx| {
+                            this.will_split_placement = None;
+
+                            // Dropping a panel from this same tab group onto
+                            // the strip moves it after the last tab.
+                            let ix = if drag.tab_panel == cx.entity() {
+                                Some(tabs_count - 1)
+                            } else {
+                                None
+                            };
+
+                            this.on_drop(drag, ix, false, window, cx);
+                        });
+                    }
+                })
+                .drag_over::<AnyDrag>(|this, _, _, cx| this.bg(cx.theme().tokens.drop_target))
+                .on_drop({
+                    let view = self.tab_panel.clone();
+                    move |item: &AnyDrag, _, cx| {
+                        view.update(cx, |this, cx| {
+                            this.will_split_placement = None;
+                            this.emit_drag_drop(item, None, cx);
+                        });
+                    }
+                });
+        }
+
+        empty.into_any_element()
+    }
+}
+
+impl RenderOnce for TabBar {
+    fn render(self, window: &mut Window, cx: &mut App) -> impl IntoElement {
+        let tabs: Vec<_> = self
+            .panels
+            .iter()
+            .enumerate()
+            .filter_map(|(ix, panel)| {
+                let mut active = self.active_panel.as_ref() == Some(panel);
+                if !panel.visible(cx) {
+                    return None;
+                }
+                // Always not show active tab style, if the panel is collapsed
+                if self.collapsed {
+                    active = false;
+                }
+                Some(self.render_tab(ix, panel.clone(), active, window, cx))
+            })
+            .collect();
+
+        let empty_space = match self.empty_space {
+            Some(empty_space) => empty_space,
+            None => self.render_empty_space(),
+        };
+
+        Tabs::new(self.id)
+            .px(px(-1.))
+            .h(TAB_BAR_HEIGHT)
+            .flex()
+            .items_center()
+            .text_color(cx.theme().tab_foreground)
+            .when_some(self.prefix, |this, prefix| this.child(prefix))
+            .child(
+                h_flex().id("tabs").flex_1().overflow_x_hidden().child(
+                    h_flex()
+                        .id("tabs-inner")
+                        .relative()
+                        .gap(px(4.))
+                        .overflow_x_scroll()
+                        .lock_scroll_axis()
+                        .track_scroll(&self.scroll_handle)
+                        .children(tabs)
+                        .when(!self.collapsed, |this| this.child(empty_space)),
+                ),
+            )
+            .when_some(self.suffix, |this, suffix| {
+                this.when(!self.collapsed, |this| this.child(suffix))
+            })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::sync::atomic::{AtomicBool, Ordering};
+
+    use gpui::{
+        Context, Entity, MouseButton, Render, TestAppContext, VisualTestContext, WindowOptions,
+        div, px, size,
+    };
+    use gpui_component::{Root, Theme, v_flex};
+
+    use super::*;
+    use crate::DockArea;
+    use crate::tab_panel::title_bar_drag_handlers;
+
+    #[derive(Default)]
+    struct ProbeFlags {
+        empty_down: AtomicBool,
+        empty_click: AtomicBool,
+        control_down: AtomicBool,
+        control_click: AtomicBool,
+    }
+
+    struct ProbeView {
+        flags: Entity<ProbeFlags>,
+        tab_panel: Entity<TabPanel>,
+    }
+
+    impl Render for ProbeView {
+        fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+            let flags = self.flags.clone();
+
+            let empty = title_bar_drag_handlers(
+                div()
+                    .id("empty-space")
+                    .h(TAB_BAR_HEIGHT)
+                    .flex_grow_1()
+                    .min_w_16(),
+                window,
+                cx,
+            )
+            .debug_selector(|| "empty-space".into())
+            .on_mouse_down(MouseButton::Left, {
+                let flags = flags.clone();
+                move |_, _, cx| flags.update(cx, |f, _| f.empty_down.store(true, Ordering::SeqCst))
+            })
+            .on_click({
+                let flags = flags.clone();
+                move |_, _, cx| flags.update(cx, |f, _| f.empty_click.store(true, Ordering::SeqCst))
+            });
+
+            let control =
+                title_bar_drag_handlers(div().id("control-space").h_8().flex_grow_1(), window, cx)
+                    .debug_selector(|| "control-space".into())
+                    .on_mouse_down(MouseButton::Left, {
+                        let flags = flags.clone();
+                        move |_, _, cx| {
+                            flags.update(cx, |f, _| f.control_down.store(true, Ordering::SeqCst))
+                        }
+                    })
+                    .on_click({
+                        let flags = flags.clone();
+                        move |_, _, cx| {
+                            flags.update(cx, |f, _| f.control_click.store(true, Ordering::SeqCst))
+                        }
+                    });
+
+            v_flex()
+                .size_full()
+                .child(TabBar::new("probe-bar", self.tab_panel.clone()).empty_space(empty))
+                .child(control)
+        }
+    }
+
+    /// Diagnostic: verify that the tab bar's trailing empty space receives
+    /// mouse events when wrapped by `title_bar_drag_handlers`, i.e. the
+    /// strip's scroll containers do not swallow them.
+    #[gpui::test]
+    fn tab_bar_empty_space_receives_events(cx: &mut TestAppContext) {
+        let (flags, handle) = cx.update(|cx| {
+            cx.set_global(Theme::default());
+            let flags = cx.new(|_| ProbeFlags::default());
+            let handle = cx.open_window(
+                WindowOptions {
+                    window_bounds: Some(gpui::WindowBounds::Windowed(gpui::Bounds {
+                        origin: gpui::Point::default(),
+                        size: size(px(800.), px(100.)),
+                    })),
+                    ..Default::default()
+                },
+                |window, cx| {
+                    let flags = flags.clone();
+                    let dock_area = cx.new(|cx| DockArea::new("probe-dock", None, window, cx));
+                    let tab_panel =
+                        cx.new(|cx| TabPanel::new(None, dock_area.downgrade(), window, cx));
+                    let content = cx.new(|_| ProbeView { flags, tab_panel });
+                    cx.new(|cx| Root::new(content, window, cx))
+                },
+            );
+            (flags, handle.unwrap())
+        });
+        let mut cx = VisualTestContext::from_window(handle.into(), cx);
+
+        cx.run_until_parked();
+        cx.update(|window, cx| {
+            _ = window.draw(cx);
+        });
+
+        let empty_bounds = cx
+            .debug_bounds("empty-space")
+            .expect("empty-space must be laid out");
+        let control_bounds = cx
+            .debug_bounds("control-space")
+            .expect("control-space must be laid out");
+        let empty_center = empty_bounds.center();
+        let control_center = control_bounds.center();
+
+        // Control: a plain div with the same handlers, outside the tab bar.
+        cx.simulate_click(control_center, Default::default());
+        // Target: the tab bar's empty-space strip.
+        cx.simulate_click(empty_center, Default::default());
+
+        let (empty_down, empty_click, control_down, control_click) = cx.read(|cx| {
+            let flags = flags.read(cx);
+            (
+                flags.empty_down.load(Ordering::SeqCst),
+                flags.empty_click.load(Ordering::SeqCst),
+                flags.control_down.load(Ordering::SeqCst),
+                flags.control_click.load(Ordering::SeqCst),
+            )
+        });
+        assert!(
+            control_down,
+            "control mouse_down must fire at {control_center:?}"
+        );
+        assert!(
+            control_click,
+            "control click must fire at {control_center:?}"
+        );
+        assert!(
+            empty_down,
+            "empty-space mouse_down must fire at {empty_center:?}"
+        );
+        assert!(
+            empty_click,
+            "empty-space click must fire at {empty_center:?}"
+        );
+    }
+}

crates/dock/src/tab_panel.rs

@@ -16,17 +16,17 @@ use gpui::{
 use gpui_component::animation::{Lerp, ease_out_cubic};
 use gpui_component::button::{Button, ButtonVariants as _};
 use gpui_component::menu::{DropdownMenu, PopupMenu};
-use gpui_component::tab::{Tab, TabBar};
 use gpui_component::{
     ActiveTheme, AxisExt, Disableable, ElementExt, IconName, Placement, Selectable, Sizable,
     h_flex, v_flex,
 };
 
+use super::tab_bar::TabBar;
 use super::{
     AnyDrag, ClosePanel, DockArea, DockEvent, DockPlacement, DropTarget, Panel, PanelControl,
     PanelEvent, PanelState, PanelView, StackPanel, ToggleZoom,
 };
-use crate::{PanelInfo, TAB_BAR_HEIGHT, t, window_controls};
+use crate::{PanelInfo, t, window_controls};
 
 #[derive(Clone)]
 struct TabState {
@@ -41,7 +41,7 @@ struct TabState {
 pub(crate) struct DragPanel {
     pub(crate) panel: Arc<dyn PanelView>,
     pub(crate) tab_panel: Entity<TabPanel>,
-    drag_offset: Rc<Cell<Point<Pixels>>>,
+    pub(crate) drag_offset: Rc<Cell<Point<Pixels>>>,
     drag_session_id: u64,
 }
 
@@ -150,7 +150,7 @@ pub struct TabPanel {
     zoomed: bool,
     collapsed: bool,
     /// When drag move, will get the placement of the panel to be split
-    will_split_placement: Option<Placement>,
+    pub(crate) will_split_placement: Option<Placement>,
     drop_placeholder_animation: Option<DropPlaceholderAnimation>,
     drop_placeholder_animation_name: SharedString,
 
@@ -160,7 +160,7 @@ pub struct TabPanel {
     title_bar_bounds: Option<Bounds<Pixels>>,
     /// Bounds of the tab bar's trailing empty space (right after the last
     /// tab), which marks where the draggable region starts.
-    title_bar_strip_bounds: Option<Bounds<Pixels>>,
+    pub(crate) title_bar_strip_bounds: Option<Bounds<Pixels>>,
     /// Bounds of the tab bar's suffix (toolbar) area, which marks where the
     /// draggable region ends.
     title_bar_suffix_bounds: Option<Bounds<Pixels>>,
@@ -342,7 +342,7 @@ impl TabPanel {
         self.active_ix
     }
 
-    fn set_active_ix(&mut self, ix: usize, window: &mut Window, cx: &mut Context<Self>) {
+    pub(crate) fn set_active_ix(&mut self, ix: usize, window: &mut Window, cx: &mut Context<Self>) {
         if ix == self.active_ix {
             return;
         }
@@ -845,10 +845,8 @@ impl TabPanel {
             self.tab_bar_scroll_handle.scroll_to_item(visible_ix);
         }
 
-        let tabs_count = self.panels.len();
-
-        // TabBar lays out its scrollable content at content width, so the
-        // strip after the last tab only spans `min_w_16` — the rest of the
+        // The tab strip lays out its scrollable content at content width, so
+        // the area after the last tab only spans `min_w_16` — the rest of the
         // tab bar has no element at all. Cover that dead zone with a
         // measured overlay so the whole non-interactive area can drag the
         // window. Its span is [last tab's right edge, suffix's left edge].
@@ -898,11 +896,13 @@ impl TabPanel {
                         }
                     })
                     .child(
-                        TabBar::new("tab-bar")
-                            .h(TAB_BAR_HEIGHT)
-                            .pill()
-                            .small()
-                            .track_scroll(&self.tab_bar_scroll_handle)
+                        TabBar::new("tab-bar", cx.entity())
+                            .panels(self.panels.clone())
+                            .active_panel(state.active_panel.clone())
+                            .collapsed(self.collapsed)
+                            .draggable(state.draggable)
+                            .droppable(state.droppable)
+                            .scroll_handle(&self.tab_bar_scroll_handle)
                             .prefix(
                                 h_flex()
                                     .items_center()
@@ -916,132 +916,6 @@ impl TabPanel {
                                     .children(left_dock_button)
                                     .child(self.render_prev_next_tab_buttons(cx)),
                             )
-                            .children(self.panels.iter().enumerate().filter_map(|(ix, panel)| {
-                                let mut active = state.active_panel.as_ref() == Some(panel);
-                                let droppable = self.collapsed;
-
-                                if !panel.visible(cx) {
-                                    return None;
-                                }
-
-                                // Always not show active tab style, if the panel is collapsed
-                                if self.collapsed {
-                                    active = false;
-                                }
-
-                                Some(
-                                    // Note: upstream also calls the crate-private `Tab::ix(ix)` and
-                                    // `Tab::tab_bar_prefix(...)` here. `TabBar` re-applies `ix` per
-                                    // child itself, and `tab_bar_prefix` only clears the first
-                                    // tab's left border when the bar has no prefix — both are
-                                    // inaccessible from outside gpui-component, so they are
-                                    // omitted.
-                                    Tab::new()
-                                        .map(|this| {
-                                            if let Some(tab_name) = panel.tab_name(cx) {
-                                                this.child(tab_name)
-                                            } else {
-                                                this.child(panel.title(window, cx))
-                                            }
-                                        })
-                                        .selected(active)
-                                        .on_click(cx.listener({
-                                            move |view, _, window, cx| {
-                                                view.set_active_ix(ix, window, cx);
-                                            }
-                                        }))
-                                        .when(!droppable, |this| {
-                                            this.when(state.draggable, |this| {
-                                                this.on_drag(
-                                                    DragPanel::new(panel.clone(), view.clone()),
-                                                    |drag, offset, _, cx| {
-                                                        cx.stop_propagation();
-                                                        drag.drag_offset.set(offset);
-                                                        cx.new(|_| drag.clone())
-                                                    },
-                                                )
-                                            })
-                                            .when(
-                                                state.droppable,
-                                                |this| {
-                                                    this.drag_over::<DragPanel>(|this, _, _, cx| {
-                                                this.rounded_l_none()
-                                                    .border_l_2()
-                                                    .border_r_0()
-                                                    .border_color(cx.theme().drag_border)
-                                            })
-                                            .on_drop(cx.listener(
-                                                move |this, drag: &DragPanel, window, cx| {
-                                                    this.will_split_placement = None;
-                                                    this.on_drop(drag, Some(ix), true, window, cx)
-                                                },
-                                            ))
-                                            .drag_over::<AnyDrag>(|this, _, _, cx| {
-                                                this.rounded_l_none()
-                                                    .border_l_2()
-                                                    .border_r_0()
-                                                    .border_color(cx.theme().drag_border)
-                                            })
-                                            .on_drop(cx.listener(
-                                                |this, item: &AnyDrag, _, cx| {
-                                                    this.will_split_placement = None;
-                                                    this.emit_drag_drop(item, None, cx);
-                                                },
-                                            ))
-                                                },
-                                            )
-                                        }),
-                                )
-                            }))
-                            .last_empty_space(
-                                // Empty space to allow dropping at the last tab. Its left
-                                // edge (right after the last tab) marks the start of the
-                                // title-bar drag overlay.
-                                div()
-                                    .id("tab-bar-empty-space")
-                                    .h_full()
-                                    .flex_grow_1()
-                                    .min_w_16()
-                                    .on_prepaint({
-                                        let view = view.clone();
-                                        move |bounds, _, cx| {
-                                            view.update(cx, |this, cx| {
-                                                if this.title_bar_strip_bounds != Some(bounds) {
-                                                    this.title_bar_strip_bounds = Some(bounds);
-                                                    cx.notify();
-                                                }
-                                            });
-                                        }
-                                    })
-                                    .when(state.droppable, |this| {
-                                        let view = view.clone();
-                                        this.drag_over::<DragPanel>(|this, _, _, cx| {
-                                            this.bg(cx.theme().tokens.drop_target)
-                                        })
-                                        .on_drop(cx.listener(
-                                            move |this, drag: &DragPanel, window, cx| {
-                                                this.will_split_placement = None;
-
-                                                let ix = if drag.tab_panel == view {
-                                                    Some(tabs_count - 1)
-                                                } else {
-                                                    None
-                                                };
-
-                                                this.on_drop(drag, ix, false, window, cx)
-                                            },
-                                        ))
-                                        .drag_over::<AnyDrag>(|this, _, _, cx| {
-                                            this.bg(cx.theme().tokens.drop_target)
-                                        })
-                                        .on_drop(
-                                            cx.listener(|this, item: &AnyDrag, _, cx| {
-                                                this.will_split_placement = None;
-                                                this.emit_drag_drop(item, None, cx);
-                                            }),
-                                        )
-                                    }),
-                            )
                             .when(!self.collapsed, |this| {
                                 this.suffix(
                                     h_flex()
@@ -1249,7 +1123,7 @@ impl TabPanel {
 
     /// Report a host-owned drag landing on this TabPanel. `placement` is `None`
     /// to merge into this tab group instead of splitting.
-    fn emit_drag_drop(
+    pub(crate) fn emit_drag_drop(
         &mut self,
         item: &AnyDrag,
         placement: Option<Placement>,
@@ -1269,7 +1143,7 @@ impl TabPanel {
     /// Handle the drop event when dragging a panel
     ///
     /// - `active` - When true, the panel will be active after the drop
-    fn on_drop(
+    pub(crate) fn on_drop(
         &mut self,
         drag: &DragPanel,
         ix: Option<usize>,
@@ -1575,11 +1449,9 @@ impl Render for TabPanel {
 #[cfg(test)]
 mod tests {
     use std::sync::Mutex;
-    use std::sync::atomic::{AtomicBool, Ordering};
 
-    use gpui::{Axis, TestAppContext, VisualTestContext, WindowHandle, WindowOptions, size};
-    use gpui_component::tab::{Tab, TabBar};
-    use gpui_component::{Root, Theme, v_flex};
+    use gpui::{Axis, TestAppContext, VisualTestContext, WindowHandle};
+    use gpui_component::{Root, Theme};
 
     use super::*;
     use crate::DockItem;
@@ -2291,140 +2163,9 @@ mod tests {
         });
     }
 
-    #[derive(Default)]
-    struct ProbeFlags {
-        empty_down: AtomicBool,
-        empty_click: AtomicBool,
-        control_down: AtomicBool,
-        control_click: AtomicBool,
-    }
-
-    struct ProbeView {
-        flags: Entity<ProbeFlags>,
-    }
-
-    impl Render for ProbeView {
-        fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
-            let flags = self.flags.clone();
-
-            let empty = title_bar_drag_handlers(
-                div().id("empty-space").h_full().flex_grow_1().min_w_16(),
-                window,
-                cx,
-            )
-            .debug_selector(|| "empty-space".into())
-            .on_mouse_down(MouseButton::Left, {
-                let flags = flags.clone();
-                move |_, _, cx| flags.update(cx, |f, _| f.empty_down.store(true, Ordering::SeqCst))
-            })
-            .on_click({
-                let flags = flags.clone();
-                move |_, _, cx| flags.update(cx, |f, _| f.empty_click.store(true, Ordering::SeqCst))
-            });
-
-            let control =
-                title_bar_drag_handlers(div().id("control-space").h_8().flex_grow_1(), window, cx)
-                    .debug_selector(|| "control-space".into())
-                    .on_mouse_down(MouseButton::Left, {
-                        let flags = flags.clone();
-                        move |_, _, cx| {
-                            flags.update(cx, |f, _| f.control_down.store(true, Ordering::SeqCst))
-                        }
-                    })
-                    .on_click({
-                        let flags = flags.clone();
-                        move |_, _, cx| {
-                            flags.update(cx, |f, _| f.control_click.store(true, Ordering::SeqCst))
-                        }
-                    });
-
-            v_flex()
-                .size_full()
-                .child(
-                    TabBar::new("probe-bar")
-                        .child(Tab::new().label("Alpha"))
-                        .child(Tab::new().label("Beta"))
-                        .suffix(div())
-                        .last_empty_space(empty),
-                )
-                .child(control)
-        }
-    }
-
-    /// Diagnostic: verify that the tab bar's `last_empty_space` element
-    /// receives mouse events when wrapped by `title_bar_drag_handlers`.
-    #[gpui::test]
-    fn tab_bar_empty_space_receives_events(cx: &mut TestAppContext) {
-        let (flags, handle) = cx.update(|cx| {
-            cx.set_global(Theme::default());
-            let flags = cx.new(|_| ProbeFlags::default());
-            let handle = cx.open_window(
-                WindowOptions {
-                    window_bounds: Some(gpui::WindowBounds::Windowed(gpui::Bounds {
-                        origin: gpui::Point::default(),
-                        size: size(px(800.), px(100.)),
-                    })),
-                    ..Default::default()
-                },
-                |window, cx| {
-                    let flags = flags.clone();
-                    let content = cx.new(|_| ProbeView { flags });
-                    cx.new(|cx| Root::new(content, window, cx))
-                },
-            );
-            (flags, handle.unwrap())
-        });
-        let mut cx = VisualTestContext::from_window(handle.into(), cx);
-
-        cx.run_until_parked();
-        cx.update(|window, cx| {
-            _ = window.draw(cx);
-        });
-
-        let empty_bounds = cx
-            .debug_bounds("empty-space")
-            .expect("empty-space must be laid out");
-        let control_bounds = cx
-            .debug_bounds("control-space")
-            .expect("control-space must be laid out");
-        let empty_center = empty_bounds.center();
-        let control_center = control_bounds.center();
-
-        // Control: a plain div with the same handlers, outside the TabBar.
-        cx.simulate_click(control_center, Default::default());
-        // Target: the TabBar's last_empty_space.
-        cx.simulate_click(empty_center, Default::default());
-
-        let (empty_down, empty_click, control_down, control_click) = cx.read(|cx| {
-            let flags = flags.read(cx);
-            (
-                flags.empty_down.load(Ordering::SeqCst),
-                flags.empty_click.load(Ordering::SeqCst),
-                flags.control_down.load(Ordering::SeqCst),
-                flags.control_click.load(Ordering::SeqCst),
-            )
-        });
-        assert!(
-            control_down,
-            "control mouse_down must fire at {control_center:?}"
-        );
-        assert!(
-            control_click,
-            "control click must fire at {control_center:?}"
-        );
-        assert!(
-            empty_down,
-            "empty-space mouse_down must fire at {empty_center:?}"
-        );
-        assert!(
-            empty_click,
-            "empty-space click must fire at {empty_center:?}"
-        );
-    }
-
     /// The title-bar drag overlay must cover the dead zone between the last
-    /// tab and the suffix (TabBar's scrollable content is content-width, so
-    /// that area has no element of its own).
+    /// tab and the suffix (the tab strip's scrollable content is
+    /// content-width, so that area has no element of its own).
     #[gpui::test]
     fn title_bar_drag_overlay_covers_the_dead_zone(cx: &mut TestAppContext) {
         let fixture = setup(cx);

crates/workspace/src/views/repo_detail/diff.rs

@@ -6,13 +6,13 @@
 use std::path::PathBuf;
 use std::rc::Rc;
 
+use dock::{Panel, PanelEvent};
 use gpui::prelude::*;
 use gpui::{
     AnyElement, App, Context, Entity, EventEmitter, FocusHandle, Focusable, Pixels, Render,
     ScrollStrategy, SharedString, Size, WeakEntity, Window, div, px, size,
 };
 use gpui_component::clipboard::Clipboard;
-use dock::{Panel, PanelEvent};
 use gpui_component::list::ListItem;
 use gpui_component::resizable::{resizable_panel, v_resizable};
 use gpui_component::scroll::{ScrollableElement, Scrollbar};
@@ -486,8 +486,6 @@ impl CommitDiffView {
 
         v_flex()
             .px_4()
-            .pt_2()
-            .pb_4()
             .w_full()
             .gap_4()
             .child(
@@ -609,8 +607,8 @@ impl Render for CommitDiffView {
         v_resizable("commit-diff")
             .child(
                 resizable_panel()
-                    .size(px(170.))
-                    .size_range(px(100.)..px(400.))
+                    .size(px(180.))
+                    .size_range(px(120.)..px(420.))
                     .flex_none()
                     .bg(cx.theme().background)
                     .child(self.render_header(cx)),

crates/workspace/src/views/repo_detail/mod.rs

@@ -941,8 +941,7 @@ impl RepoDetailView {
 
         v_flex()
             .px_4()
-            .pt_2()
-            .pb_2()
+            .pb_4()
             .w_full()
             .gap_8()
             .border_b_1()
@@ -1213,16 +1212,19 @@ impl Render for RepoDetailView {
         v_flex()
             .id("repo")
             .size_full()
+            .gap_4()
             .child(self.render_header(cx))
-            .child(match self.active_tab {
-                0 => h_flex()
+            .map(|this| match self.active_tab {
+                0 => this.child(
+                    h_flex()
                         .flex_1()
                         .w_full()
                         .overflow_hidden()
                         .child(Self::render_tree_column(tree_state, view, cx))
                         .child(self.render_content_column(pane_title, cx))
                         .into_any_element(),
-                _ => self.render_commits_tab(cx),
+                ),
+                _ => this.child(self.render_commits_tab(cx)),
             })
     }
 }

crates/workspace/src/views/sidebar/mod.rs

@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 use assets::CustomIconName;
-use dock::{DockArea, DockPlacement, Panel, PanelEvent, title_bar_drag_handlers};
+use dock::{DockArea, DockPlacement, Panel, PanelEvent, TAB_BAR_HEIGHT, title_bar_drag_handlers};
 use gpui::prelude::*;
 use gpui::{
     App, ClickEvent, Context, ElementId, EventEmitter, FocusHandle, Focusable, Render,
@@ -11,7 +11,7 @@ use gpui_component::avatar::Avatar;
 use gpui_component::button::{Button, ButtonVariants};
 use gpui_component::input::InputState;
 use gpui_component::{ActiveTheme, Icon, IconName, Sizable, StyledExt, h_flex, v_flex};
-use signed_state::{Backend, BackendEvent, ProfileStore};
+use signed_state::{Backend, BackendEvent, Profile, ProfileStore};
 
 use super::RepoListView;
 
@@ -100,6 +100,42 @@ impl SidebarPanel {
     fn open_import(&mut self, window: &mut Window, cx: &mut Context<Self>) {
         import_dialog::open(window, cx);
     }
+
+    /// Render the user avatar and name in the sidebar, wrapped in the window titlebar drag area.
+    fn render_user(
+        &self,
+        profile: &Profile,
+        window: &mut Window,
+        cx: &mut Context<Self>,
+    ) -> impl IntoElement {
+        let name = profile.name();
+        let picture = profile.picture();
+
+        title_bar_drag_handlers(
+            h_flex()
+                .id("user")
+                .h(TAB_BAR_HEIGHT)
+                .when(cfg!(target_os = "macos"), |this| this.pl(px(80.)))
+                .child(
+                    div().child(
+                        Button::new("user").text().dropdown_caret(true).child(
+                            h_flex()
+                                .gap_1()
+                                .child(
+                                    Avatar::new()
+                                        .name(name.clone())
+                                        .when_some(picture, |this, url| this.src(url))
+                                        .small()
+                                        .border_0(),
+                                )
+                                .child(div().text_xs().font_semibold().child(name)),
+                        ),
+                    ),
+                ),
+            window,
+            cx,
+        )
+    }
 }
 
 impl Panel for SidebarPanel {
@@ -180,30 +216,7 @@ impl Render for SidebarPanel {
                 div()
                     .flex_1()
                     .when_some(profile.as_ref(), |this, profile| {
-                        let name = profile.name();
-                        let picture = profile.picture();
-
-                        this.child(title_bar_drag_handlers(
-                            h_flex()
-                                .id("sidebar-profile")
-                                .h_12()
-                                .px_3()
-                                .gap_2()
-                                // The macOS traffic lights overlay the
-                                // top-left corner of the window; keep the
-                                // profile content clear of them.
-                                .when(cfg!(target_os = "macos"), |this| this.pl(px(80.)))
-                                .child(
-                                    Avatar::new()
-                                        .name(name.clone())
-                                        .when_some(picture, |this, url| this.src(url))
-                                        .small()
-                                        .border_0(),
-                                )
-                                .child(div().text_sm().child(name)),
-                            window,
-                            cx,
-                        ))
+                        this.child(self.render_user(profile, window, cx))
                     })
                     .child(
                         v_flex()

desktop/src/main.rs

@@ -1,6 +1,7 @@
 use std::sync::Arc;
 
 use assets::Assets;
+use dock::TAB_BAR_HEIGHT;
 use gpui::*;
 use gpui_component::theme;
 use gpui_platform::application;
@@ -53,7 +54,11 @@ fn main() {
                 app_id: Some("Signed".to_owned()),
                 titlebar: Some(TitlebarOptions {
                     title: Some(SharedString::new_static("Signed")),
-                    traffic_light_position: Some(point(px(9.0), px(9.0))),
+                    // AppKit's traffic-light buttons are 14 pt tall; offset them so their vertical center matches the tab bar.
+                    traffic_light_position: Some(point(
+                        px(9.0),
+                        px(TAB_BAR_HEIGHT / px(2.) - 14. / 2.),
+                    )),
                     appears_transparent: true,
                 }),
                 app_owns_titlebar_drag: true,