fix: Ensure cursor syncs with more than just focused blocks

core/interfaces/i_navigable.ts

@@ -29,3 +29,13 @@ export interface INavigable<T> {
    */
   getClass(): new (...args: any) => T;
 }
+
+/**
+ * Determines whether the provided object fulfills the contract of INavigable.
+ *
+ * @param object The object to test.
+ * @returns Whether the provided object can be used as an INavigable.
+ */
+export function isNavigable(object: any | null): object is INavigable<any> {
+  return object && 'isNavigable' in object && 'getClass' in object;
+}

core/keyboard_nav/line_cursor.ts

@@ -26,7 +26,7 @@ import {FlyoutButton} from '../flyout_button.js';
 import {FlyoutSeparator} from '../flyout_separator.js';
 import {getFocusManager} from '../focus_manager.js';
 import {isFocusableNode} from '../interfaces/i_focusable_node.js';
-import type {INavigable} from '../interfaces/i_navigable.js';
+import {isNavigable, type INavigable} from '../interfaces/i_navigable.js';
 import * as registry from '../registry.js';
 import {RenderedConnection} from '../rendered_connection.js';
 import {Renderer} from '../renderers/zelos/renderer.js';
@@ -593,11 +593,10 @@ export class LineCursor extends Marker {
   private updateCurNodeFromFocus() {
     const focused = getFocusManager().getFocusedNode();
 
-    if (focused instanceof BlockSvg) {
-      const block: BlockSvg | null = focused;
-      if (block && block.workspace === this.workspace) {
-        this.setCurNode(block);
-      }
+    if (isNavigable(focused)) {
+      const block = this.getSourceBlockFromNode(focused);
+      if (block && block.workspace !== this.workspace) return;
+      this.setCurNode(focused);
     }
   }