diff --git a/arduino-ide-extension/src/browser/theia/core/application-shell.ts b/arduino-ide-extension/src/browser/theia/core/application-shell.ts
index d3d7cc2f..9f0ac6b7 100644
--- a/arduino-ide-extension/src/browser/theia/core/application-shell.ts
+++ b/arduino-ide-extension/src/browser/theia/core/application-shell.ts
@@ -1,28 +1,20 @@
-import { injectable, inject } from '@theia/core/shared/inversify';
-import { EditorWidget } from '@theia/editor/lib/browser';
-import { MessageService } from '@theia/core/lib/common/message-service';
-import { OutputWidget } from '@theia/output/lib/browser/output-widget';
-import {
-  ConnectionStatusService,
-  ConnectionStatus,
-} from '@theia/core/lib/browser/connection-status-service';
 import {
   ApplicationShell as TheiaApplicationShell,
   DockPanel,
   DockPanelRenderer as TheiaDockPanelRenderer,
   Panel,
+  SaveOptions,
+  SHELL_TABBAR_CONTEXT_MENU,
   TabBar,
   Widget,
-  SHELL_TABBAR_CONTEXT_MENU,
-  SaveOptions,
 } from '@theia/core/lib/browser';
-import { Sketch } from '../../../common/protocol';
 import {
-  CurrentSketch,
-  SketchesServiceClientImpl,
-} from '../../../common/protocol/sketches-service-client-impl';
-import { nls } from '@theia/core/lib/common';
-import URI from '@theia/core/lib/common/uri';
+  ConnectionStatus,
+  ConnectionStatusService,
+} from '@theia/core/lib/browser/connection-status-service';
+import { nls } from '@theia/core/lib/common/nls';
+import { MessageService } from '@theia/core/lib/common/message-service';
+import { inject, injectable } from '@theia/core/shared/inversify';
 import { ToolbarAwareTabBar } from './tab-bars';
 
 @injectable()
@@ -30,40 +22,9 @@ export class ApplicationShell extends TheiaApplicationShell {
   @inject(MessageService)
   private readonly messageService: MessageService;
 
-  @inject(SketchesServiceClientImpl)
-  private readonly sketchesServiceClient: SketchesServiceClientImpl;
-
   @inject(ConnectionStatusService)
   private readonly connectionStatusService: ConnectionStatusService;
 
-  protected override track(widget: Widget): void {
-    super.track(widget);
-    if (widget instanceof OutputWidget) {
-      widget.title.closable = false; // TODO: https://arduino.slack.com/archives/C01698YT7S4/p1598011990133700
-    }
-    if (widget instanceof EditorWidget) {
-      // Make the editor un-closeable asynchronously.
-      this.sketchesServiceClient.currentSketch().then((sketch) => {
-        if (CurrentSketch.isValid(sketch)) {
-          if (!this.isSketchFile(widget.editor.uri, sketch.uri)) {
-            return;
-          }
-          if (Sketch.isInSketch(widget.editor.uri, sketch)) {
-            widget.title.closable = false;
-          }
-        }
-      });
-    }
-  }
-
-  private isSketchFile(uri: URI, sketchUriString: string): boolean {
-    const sketchUri = new URI(sketchUriString);
-    if (uri.parent.isEqual(sketchUri)) {
-      return true;
-    }
-    return false;
-  }
-
   override async addWidget(
     widget: Widget,
     options: Readonly<TheiaApplicationShell.WidgetOptions> = {}
diff --git a/arduino-ide-extension/src/browser/theia/core/widget-manager.ts b/arduino-ide-extension/src/browser/theia/core/widget-manager.ts
index 4e8e1013..87d0ae74 100644
--- a/arduino-ide-extension/src/browser/theia/core/widget-manager.ts
+++ b/arduino-ide-extension/src/browser/theia/core/widget-manager.ts
@@ -7,6 +7,7 @@ import {
   postConstruct,
 } from '@theia/core/shared/inversify';
 import { EditorWidget } from '@theia/editor/lib/browser';
+import { OutputWidget } from '@theia/output/lib/browser/output-widget';
 import deepEqual = require('deep-equal');
 import {
   CurrentSketch,
@@ -21,19 +22,50 @@ export class WidgetManager extends TheiaWidgetManager {
 
   @postConstruct()
   protected init(): void {
-    this.sketchesServiceClient.onCurrentSketchDidChange((currentSketch) => {
-      if (CurrentSketch.isValid(currentSketch)) {
-        const sketchFileUris = new Set(Sketch.uris(currentSketch));
-        for (const widget of this.widgets.values()) {
-          if (widget instanceof EditorWidget) {
-            const uri = widget.editor.uri.toString();
-            if (sketchFileUris.has(uri)) {
-              widget.title.closable = false;
-            }
-          }
+    this.sketchesServiceClient.onCurrentSketchDidChange((sketch) =>
+      this.maybeSetWidgetUncloseable(
+        sketch,
+        ...Array.from(this.widgets.values())
+      )
+    );
+  }
+
+  override getOrCreateWidget<T extends Widget>(
+    factoryId: string,
+    options?: unknown
+  ): Promise<T> {
+    const unresolvedWidget = super.getOrCreateWidget<T>(factoryId, options);
+    unresolvedWidget.then(async (widget) => {
+      const sketch = await this.sketchesServiceClient.currentSketch();
+      this.maybeSetWidgetUncloseable(sketch, widget);
+    });
+    return unresolvedWidget;
+  }
+
+  private maybeSetWidgetUncloseable(
+    sketch: CurrentSketch,
+    ...widgets: Widget[]
+  ): void {
+    const sketchFileUris =
+      CurrentSketch.isValid(sketch) && new Set(Sketch.uris(sketch));
+    for (const widget of widgets) {
+      if (widget instanceof OutputWidget) {
+        this.setWidgetUncloseable(widget); // TODO: https://arduino.slack.com/archives/C01698YT7S4/p1598011990133700
+      } else if (widget instanceof EditorWidget) {
+        // Make the editor un-closeable asynchronously.
+        const uri = widget.editor.uri.toString();
+        if (!!sketchFileUris && sketchFileUris.has(uri)) {
+          this.setWidgetUncloseable(widget);
         }
       }
-    });
+    }
+  }
+
+  private setWidgetUncloseable(widget: Widget): void {
+    const { title } = widget;
+    if (title.closable) {
+      title.closable = false;
+    }
   }
 
   /**