fix(ui): show Preferences checkbox outlines in every theme

Reapply on current upstream main.

crates/ui-egui/src/prefs_dialog.rs

@@ -363,9 +363,10 @@ fn picas_in_use(d: &Dialog) -> bool {
 }
 
 fn bool_row(ui: &mut egui::Ui, d: &mut Dialog, key: &str, label: &str) {
-    let mut b = d.bool(key);
-    if ui.checkbox(&mut b, tl!(label)).changed() {
-        d.fields.insert(key.into(), json!(b));
+    // Use the same outlined checkbox as the rest of the app. egui's default
+    // checkbox inherits an invisible resting border from the panel theme.
+    if widgets::check(ui, tl!(label), d.bool(key), ui.is_enabled()) {
+        d.fields.insert(key.into(), json!(!d.bool(key)));
     }
 }
 
@@ -386,6 +387,30 @@ mod tests {
     use crate::Services;
     use vectorcraft_engine::Session;
 
+    /// A resting checkbox must have a visible outline in both states and every brightness.
+    #[test]
+    fn preference_checkboxes_draw_outlines_without_hover() {
+        for brightness in Brightness::ALL {
+            let ctx = egui::Context::default();
+            crate::theme::install_fonts(&ctx);
+            theme::apply(&ctx, brightness);
+            for checked in [false, true] {
+                let mut d = Dialog::new("preferences", json!({"showToolTips": checked}));
+                let raw = egui::RawInput {
+                    screen_rect: Some(egui::Rect::from_min_size(egui::Pos2::ZERO, egui::vec2(400.0, 200.0))),
+                    ..Default::default()
+                };
+                let mut out = ctx.run_ui(raw, |ui| bool_row(ui, &mut d, "showToolTips", "Show Tool Tips"));
+                out.textures_delta.clear();
+                let outlined = out.shapes.iter().any(|shape| match &shape.shape {
+                    egui::Shape::Rect(r) => r.stroke.width > 0.0 && r.rect.width() <= 24.0 && r.rect.height() <= 24.0,
+                    _ => false,
+                });
+                assert!(outlined, "{brightness:?}, checked={checked}: no checkbox outline");
+            }
+        }
+    }
+
     /// User Interface › Canvas Color (#663): White and the three greys paint the canvas around the
     /// artboards; Match User Interface Brightness keeps the theme's.
     #[test]