diff --git a/arduino-ide-extension/src/browser/arduino-frontend-contribution.tsx b/arduino-ide-extension/src/browser/arduino-frontend-contribution.tsx
index ecdc465f..6ae68ce1 100644
--- a/arduino-ide-extension/src/browser/arduino-frontend-contribution.tsx
+++ b/arduino-ide-extension/src/browser/arduino-frontend-contribution.tsx
@@ -22,7 +22,7 @@ import { ArduinoToolbar } from './toolbar/arduino-toolbar';
 import { EditorManager, EditorMainMenu } from '@theia/editor/lib/browser';
 import { ContextMenuRenderer, OpenerService, Widget, StatusBar } from '@theia/core/lib/browser';
 import { OpenFileDialogProps, FileDialogService } from '@theia/filesystem/lib/browser/file-dialog';
-import { FileSystem } from '@theia/filesystem/lib/common';
+import { FileSystem, FileStat } from '@theia/filesystem/lib/common';
 import { ArduinoToolbarContextMenu } from './arduino-file-menu';
 import { Sketch, SketchesService } from '../common/protocol/sketches-service';
 import { WindowService } from '@theia/core/lib/browser/window/window-service';
@@ -30,7 +30,8 @@ import { CommonCommands, CommonMenus } from '@theia/core/lib/browser/common-fron
 import { FileSystemCommands } from '@theia/filesystem/lib/browser/filesystem-frontend-contribution';
 import { FileDownloadCommands } from '@theia/filesystem/lib/browser/download/file-download-command-contribution';
 import { MonacoMenus } from '@theia/monaco/lib/browser/monaco-menu';
-import {TerminalMenus} from '@theia/terminal/lib/browser/terminal-frontend-contribution';
+import { TerminalMenus } from '@theia/terminal/lib/browser/terminal-frontend-contribution';
+import { MaybePromise } from '@theia/core/lib/common/types';
 import { SelectBoardDialog } from './boards/select-board-dialog';
 import { BoardsToolBarItem } from './boards/boards-toolbar-item';
 
@@ -383,8 +384,13 @@ export class ArduinoFrontendContribution implements TabBarToolbarContribution, C
         if (destinationFileUri) {
             const destinationFile = await this.fileSystem.getFileStat(destinationFileUri.toString());
             if (destinationFile && !destinationFile.isDirectory) {
-                await this.openSketchFilesInNewWindow(destinationFileUri.toString());
-                return destinationFileUri;
+                const message = await this.validate(destinationFile);
+                if (!message) {
+                    await this.openSketchFilesInNewWindow(destinationFileUri.toString());
+                    return destinationFileUri;
+                } else {
+                    this.messageService.warn(message);
+                }
             }
         }
         return undefined;
@@ -401,8 +407,24 @@ export class ArduinoFrontendContribution implements TabBarToolbarContribution, C
         return widget;
     }
 
+    /**
+     * Returns `undefined` if the `file` is valid. Otherwise, returns with the validation error message.
+     */
+    protected validate(file: FileStat): MaybePromise<string | undefined> {
+        const uri = new URI(file.uri);
+        const path = uri.path;
+        const { name, ext, dir } = path;
+        if (ext !== '.ino') {
+            return "Only sketches with '.ino' extension can be opened.";
+        }
+        if (name !== dir.name) {
+            return `The file "${name}${ext}" needs to be inside a sketch folder named "${name}".`;
+        }
+        return undefined;
+    }
+
     // private async onNoBoardsInstalled() {
-    //     const action = await this.messageService.info("You have no boards installed. Use the boards mangager to install one.", "Open Boards Manager");
+    //     const action = await this.messageService.info("You have no boards installed. Use the boards manager to install one.", "Open Boards Manager");
     //     if (!action) {
     //         return;
     //     }
diff --git a/arduino-ide-extension/src/browser/sketch-factory.ts b/arduino-ide-extension/src/browser/sketch-factory.ts
index ff286e97..efb70981 100644
--- a/arduino-ide-extension/src/browser/sketch-factory.ts
+++ b/arduino-ide-extension/src/browser/sketch-factory.ts
@@ -1,7 +1,7 @@
 import { injectable, inject } from "inversify";
 import URI from "@theia/core/lib/common/uri";
-import { OpenerService } from "@theia/core/lib/browser";
 import { FileSystem } from "@theia/filesystem/lib/common";
+import { WindowService } from "@theia/core/lib/browser/window/window-service";
 
 @injectable()
 export class SketchFactory {
@@ -9,8 +9,8 @@ export class SketchFactory {
     @inject(FileSystem)
     protected readonly fileSystem: FileSystem;
 
-    @inject(OpenerService)
-    protected readonly openerService: OpenerService;
+    @inject(WindowService)
+    protected readonly windowService: WindowService;
 
     public async createNewSketch(parent: URI): Promise<void> {
         const monthNames = ["january", "february", "march", "april", "may", "june",
@@ -49,8 +49,9 @@ void loop() {
 
 }
 `                   });
-            const opener = await this.openerService.getOpener(sketchFile)
-            opener.open(sketchFile, { reveal: true });
+            const location = new URL(window.location.href);
+            location.searchParams.set('sketch', sketchFile.toString());
+            this.windowService.openNewWindow(location.toString());
         } catch (e) {
             throw new Error("Cannot create new sketch: " + e);
         }
diff --git a/arduino-ide-extension/src/node/core-client-provider-impl.ts b/arduino-ide-extension/src/node/core-client-provider-impl.ts
index 8a980a41..853f0725 100644
--- a/arduino-ide-extension/src/node/core-client-provider-impl.ts
+++ b/arduino-ide-extension/src/node/core-client-provider-impl.ts
@@ -90,7 +90,7 @@ export class CoreClientProviderImpl implements CoreClientProvider {
             throw new Error(`Could not retrieve instance from the initialize response.`);
         }
 
-        // in a seperate promise, try and update the index
+        // in a separate promise, try and update the index
         let succeeded = true;
         for (let i = 0; i < 10; i++) {
             try {
@@ -118,11 +118,24 @@ export class CoreClientProviderImpl implements CoreClientProvider {
         const updateReq = new UpdateIndexReq();
         updateReq.setInstance(instance);
         const updateResp = client.updateIndex(updateReq);
+        let file: string | undefined;
         updateResp.on('data', (o: UpdateIndexResp) => {
             const progress = o.getDownloadProgress();
             if (progress) {
+                if (!file && progress.getFile()) {
+                    file = `${progress.getFile()}`;
+                }
                 if (progress.getCompleted()) {
-                    this.toolOutputService.publishNewOutput("daemon", `Download${progress.getFile() ? ` of ${progress.getFile()}` : ''} completed.\n`);
+                    if (file) {
+                        if (/\s/.test(file)) {
+                            this.toolOutputService.publishNewOutput("daemon", `${file} completed.\n`);
+                        } else {
+                            this.toolOutputService.publishNewOutput("daemon", `Download of '${file}' completed.\n'`);
+                        }
+                    } else {
+                        this.toolOutputService.publishNewOutput("daemon", `The index has been successfully updated.\n'`);
+                    }
+                    file = undefined;
                 }
             }
         });