Layers: Alt-click selects only on the drawn name, and in an isolated layer

An Alt-click right of a short layer name, inside the wider rename
target, no longer replaces the selection. The isolated layer's own row
now selects the art inside it (layer.selectAll), where it cleared the
selection before. The doc line says the click selects visible, unlocked
art and clears the selection on a hidden or locked layer.

crates/engine/src/tests/menucmds.rs

@@ -1602,6 +1602,20 @@ fn layers_panel_selects_nothing_outside_the_isolated_group() {
     assert_eq!(selected(&s), vec![b]);
 }
 
+/// In isolation mode the selection column of the isolated layer's own row selects the art on it.
+#[test]
+fn layers_panel_selects_the_art_of_the_isolated_layer() {
+    let mut s = session();
+    let a = rect(&mut s, 0.0, 0.0, 50.0, 50.0);
+    let b = rect(&mut s, 100.0, 0.0, 50.0, 50.0);
+    let layer = s.active().unwrap().doc.layers[0].id;
+    s.execute("object.isolate", &json!({"id": layer.0})).unwrap();
+    s.execute("layer.selectAll", &json!({"id": layer.0})).unwrap();
+    let mut got = selected(&s);
+    got.sort_by_key(|i| i.0);
+    assert_eq!(got, vec![a, b]);
+}
+
 /// In isolation mode a recalled selection leaves out the objects outside the isolated group, and
 /// Next Object Above selects nothing outside it.
 #[test]