Fix recents menu not getting updated after loading history (#16149)

* Fix recents menu not getting updated after loading history

* Update items even before first change from manager, add isEnabled

on the clear recent documents command.

packages/docmanager-extension/src/recents.ts

@@ -67,6 +67,9 @@ export const recentsManagerPlugin: JupyterFrontEndPlugin<IRecentsManager> = {
       execute: () => {
         recentsManager.clearRecents();
       },
+      isEnabled: () =>
+        recentsManager.recentlyOpened.length != 0 ||
+        recentsManager.recentlyClosed.length != 0,
       label: trans.__('Clear Recent Documents'),
       caption: trans.__('Clear the list of recently opened items.')
     });

packages/docmanager/src/recents.ts

@@ -218,6 +218,7 @@ export class RecentsManager implements IRecentsManager {
         type as 'opened' | 'closed'
       );
     }
+    this._recentsChanged.emit(undefined);
   }
 
   /**

packages/docmanager/test/recents.spec.ts

@@ -46,6 +46,19 @@ describe('@jupyterlab/docmanager', () => {
       it('should create a new recents manager', () => {
         expect(manager).toBeInstanceOf(RecentsManager);
       });
+
+      it('should emit `changed` signal after loading', async () => {
+        const stateDB = new StateDB();
+        const done = new PromiseDelegate<boolean>();
+        manager = new TestRecentsManager({
+          stateDB,
+          contents: services.contents
+        });
+        manager.changed.connect(() => {
+          done.resolve(true);
+        });
+        expect(await done.promise).toBe(true);
+      });
     });
 
     describe('#isDisposed', () => {

packages/mainmenu-extension/src/recents.ts

@@ -52,6 +52,7 @@ class RecentsMenu extends Menu {
     super(options);
     this._manager = options.manager;
     this._showDirectories = options.showDirectories;
+    this.updateItems();
     this._manager.changed.connect(this.updateItems, this);
   }
 
@@ -230,7 +231,7 @@ export const recentsMenuPlugin: JupyterFrontEndPlugin<void> = {
     });
     submenu.title.label = trans.__('Open Recent');
     mainMenu.fileMenu.addItem({
-      type: 'submenu' as Menu.ItemType,
+      type: 'submenu',
       submenu,
       rank: 1
     });