toggling the left pane will toggle the focus between tree and detail, #3563

src/public/app/widgets/note_tree.js

@@ -887,6 +887,11 @@ export default class NoteTreeWidget extends NoteContextAwareWidget {
         }
     }
 
+    async focusTreeEvent() {
+        this.tree.$container.focus();
+        this.tree.setFocus(true);
+    }
+
     /** @returns {FancytreeNode} */
     async getNodeFromPath(notePath, expand = false, logErrors = true) {
         utils.assertArguments(notePath);