M1: a click on the toolbar no longer reaches the canvas under it (#307)

crates/ui-egui/src/pen_mode_tests.rs

@@ -92,3 +92,19 @@ fn the_mode_switcher_ends_the_pen_path_too() {
         assert_eq!(layers(&u), finished, "{label}: the path is kept as Escape keeps it");
     }
 }
+
+#[test]
+fn a_press_on_the_mode_switcher_does_not_reach_the_canvas() {
+    // The switcher floats over the canvas: the pen must not place an anchor under it.
+    for label in ["Prototype", "Design"] {
+        let mut u = Ui::new(Session::new());
+        u.app.run("tool.set", json!({"tool": "pen"}));
+        let at = mode_button(&mut u, label);
+        u.button(at, true);
+        assert!(u.app.session.tool.pen.is_none(), "{label}: the press starts no path");
+        u.button(at, false);
+        u.frame(vec![]);
+        assert!(u.app.session.tool.pen.is_none(), "{label}: no path after the click");
+        assert_eq!(layers(&u), 0, "{label}: the click adds nothing");
+    }
+}

crates/ui-egui/src/toolbar.rs

@@ -329,6 +329,10 @@ fn builder_toolbar(app: &mut FigApp, ui: &mut Ui) {
 /// toolbar region keyboard navigation moves through.
 fn pill(ui: &Ui, nav: &mut Nav, canvas: Rect, width: f32, t: &Tokens) -> Rect {
     let rect = Rect::from_center_size(pos2(canvas.center().x, canvas.max.y - 12.0 - 24.0), vec2(width, 48.0));
+    // The pill takes the press and the drag over it: its buttons sense clicks only, and egui gives
+    // a drag the canvas under them would sense to the canvas, so the pen placed an anchor there.
+    // Not focusable: the keyboard walks the buttons, not the pill.
+    ui.interact(rect, ui.id().with("pill"), Sense::CLICK | Sense::DRAG);
     a11y::area(nav, Region::Toolbar, rect);
     a11y::container_bounds(ui, rect);
     let painter = ui.painter();