Browser fold arrows: each row is one widget with a stable id, and where the click lands decides what it does (fold arrow with padding, eye, radio, or the row), so an arrow click toggles without also selecting or picking the row or starting a drag; Collapse/Expand tips; ui.at {browser|chevron} and ui.browser for automation; scenario browser_chevrons clicks every folder's arrow (document settings, named views, origin, groups, sketches, construction, canvases, components, bodies, the design) and checks the children; the inch-width units test runs now that params reads unit-less lengths in design units

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/ui-egui/src/browser.rs

@@ -17,6 +17,17 @@ use crate::context_menu::{Item, Target};
 use crate::theme::Tokens;
 use crate::{SolveApp, icons};
 
+thread_local! {
+    /// The rows drawn this frame: (label, row, fold arrow area, open). For automation
+    /// (`ui.at {browser | chevron}`, `ui.browser`).
+    static DRAWN: std::cell::RefCell<Vec<(String, Rect, Option<Rect>, Option<bool>)>> = const { std::cell::RefCell::new(Vec::new()) };
+}
+
+/// The rows on screen: (label, row rect, fold arrow area, open).
+pub fn drawn_rows() -> Vec<(String, Rect, Option<Rect>, Option<bool>)> {
+    DRAWN.with(|d| d.borrow().clone())
+}
+
 /// Browser state kept between frames.
 #[derive(Default)]
 pub struct TreeState {
@@ -246,6 +257,8 @@ struct RowResp {
     hovered: bool,
     /// The row's response (drag and drop).
     resp: Option<egui::Response>,
+    /// The press began on the fold arrow, eye or radio (not a drag of the row).
+    on_control: bool,
 }
 
 fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
@@ -256,7 +269,10 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         ui.allocate_space(r.size());
         return RowResp { rect: Some(r), ..Default::default() };
     }
-    let (r, resp) = ui.allocate_exact_size(vec2(ui.available_width(), ROW_H), Sense::click_and_drag());
+    // A stable id per row (not the layout position), so a press and its release stay on the
+    // same row while rows above open or close.
+    let (r, _) = ui.allocate_exact_size(vec2(ui.available_width(), ROW_H), Sense::hover());
+    let resp = ui.interact(r, id, Sense::click_and_drag());
     // While something is dragged (an appearance swatch, drawn under the pointer) `hovered` is
     // off; the row under the pointer still counts, so a drop lands on it.
     let dragged_over = egui::DragAndDrop::has_any_payload(ui.ctx()) && ui.input(|i| i.pointer.hover_pos()).is_some_and(|p| r.contains(p));
@@ -269,6 +285,27 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
     let mut x = r.left() + 2.0 + row.depth as f32 * INDENT;
     let cy = r.center().y;
     let ink = if row.dim { t.text_dim } else { t.icon };
+    // The row is one widget: where a click lands decides what it does (the fold arrow with
+    // padding, the eye, the radio, or the row itself), so a click on the arrow never also
+    // selects the row or starts a drag.
+    let fold_r = Rect::from_min_max(pos2(x - 4.0, r.top()), pos2(x + 15.0, r.bottom()));
+    let eye_r = Rect::from_center_size(pos2(x + 14.0 + 8.0, cy), vec2(19.0, r.height()));
+    let radio_r = Rect::from_center_size(pos2(x + 32.0 + 6.0, cy), vec2(15.0, r.height()));
+    let at = |p: Pos2| -> u8 {
+        if row.fold.is_some() && fold_r.contains(p) {
+            1
+        } else if row.eye.is_some() && eye_r.contains(p) {
+            2
+        } else if row.radio.is_some() && radio_r.contains(p) {
+            3
+        } else {
+            0
+        }
+    };
+    DRAWN.with(|d| d.borrow_mut().push((row.label.to_string(), r, row.fold.map(|_| fold_r), row.fold)));
+    let press_on = ui.input(|i| i.pointer.press_origin()).map_or(0, at);
+    let click_on = resp.interact_pointer_pos().map_or(0, at);
+    let hover_on = resp.hover_pos().map_or(0, at);
     // Fold arrow.
     if let Some(open) = row.fold {
         let ar = Rect::from_center_size(pos2(x + 6.0, cy), vec2(12.0, 12.0));
@@ -277,9 +314,10 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         } else {
             vec![pos2(ar.left() + 4.0, ar.top() + 2.0), pos2(ar.right() - 3.0, ar.center().y), pos2(ar.left() + 4.0, ar.bottom() - 2.0)]
         };
-        ui.painter().add(egui::Shape::convex_polygon(pts, t.text_dim, Stroke::NONE));
-        out.fold = ui.interact(ar.expand(3.0), id.with("fold"), Sense::click()).clicked();
-        crate::scenario::publish_handle(&format!("fold:{}", row.label), ar.center());
+        let ink = if hover_on == 1 { t.text } else { t.text_dim };
+        ui.painter().add(egui::Shape::convex_polygon(pts, ink, Stroke::NONE));
+        out.fold = resp.clicked() && click_on == 1;
+        crate::scenario::publish_handle(&format!("fold:{}", row.label), fold_r.center());
     }
     x += 14.0;
     // Eye.
@@ -289,9 +327,7 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         if !vis {
             ui.painter().line_segment([er.left_bottom() + vec2(2.0, -2.0), er.right_top() + vec2(-2.0, 2.0)], Stroke::new(1.4, t.text_dim));
         }
-        let e = ui.interact(er.expand(2.0), id.with("eye"), Sense::click());
-        out.eye = e.clicked();
-        e.on_hover_text(if vis { "Hide" } else { "Show" });
+        out.eye = resp.clicked() && click_on == 2;
     }
     x += 18.0;
     // Activation radio (components).
@@ -301,9 +337,7 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         if active {
             ui.painter().circle_filled(rc, 2.8, t.accent);
         }
-        let rr = ui.interact(Rect::from_center_size(rc, vec2(14.0, 14.0)), id.with("radio"), Sense::click());
-        out.radio = rr.clicked();
-        rr.on_hover_text(if active { "Active component" } else { "Activate" });
+        out.radio = resp.clicked() && click_on == 3;
         x += 15.0;
     }
     if !row.icon.is_empty() {
@@ -322,9 +356,20 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         bx += 15.0;
     }
     crate::scenario::publish_handle(&format!("row:{}", row.label), r.center());
+    let tip = match hover_on {
+        1 => Some(if row.fold == Some(true) { "Collapse" } else { "Expand" }),
+        2 => Some(if row.eye == Some(true) { "Hide" } else { "Show" }),
+        3 => Some(if row.radio == Some(true) { "Active component" } else { "Activate" }),
+        _ => None,
+    };
+    let resp = match tip {
+        Some(t) => resp.on_hover_text(t),
+        None => resp,
+    };
+    out.on_control = press_on != 0;
+    out.clicked = resp.clicked() && click_on == 0;
+    out.double = resp.double_clicked() && click_on == 0;
     out.resp = Some(resp.clone());
-    out.clicked = resp.clicked();
-    out.double = resp.double_clicked();
     if resp.secondary_clicked() {
         out.secondary = resp.interact_pointer_pos().or(Some(r.left_bottom()));
     }
@@ -424,6 +469,7 @@ struct Actions {
 pub fn browser(app: &mut SolveApp, ui: &mut egui::Ui) {
     let t = Tokens::get();
     app.tree.order.clear();
+    DRAWN.with(|d| d.borrow_mut().clear());
     let mut acts = Actions::default();
     egui::Panel::left("sc_browser")
         .exact_size(250.0)
@@ -1227,7 +1273,7 @@ fn entry_row(
     }
     let Some(resp) = &r.resp else { return };
     // Drag: the selected items of this folder when this one is selected, else just this one.
-    if resp.drag_started() {
+    if resp.drag_started() && !r.on_control {
         let keys: Vec<String> = if e.selected { selected_keys(app, comp, folder) } else { vec![e.key.clone()] };
         resp.dnd_set_drag_payload(Drag { comp, folder, keys });
     }