diff --git a/src/vs/platform/windows/common/windows.ts b/src/vs/platform/windows/common/windows.ts
index e9c4176128e..d835722e434 100644
--- a/src/vs/platform/windows/common/windows.ts
+++ b/src/vs/platform/windows/common/windows.ts
@@ -42,6 +42,7 @@ export interface IWindowsService {
 	clearRecentlyOpened(): Promise<void>;
 	getRecentlyOpened(windowId: number): Promise<IRecentlyOpened>;
 	isFocused(windowId: number): Promise<boolean>;
+	getActiveWindowId(): Promise<number | undefined>;
 }
 
 export const IWindowService = createDecorator<IWindowService>('windowService');
diff --git a/src/vs/platform/windows/common/windowsIpc.ts b/src/vs/platform/windows/common/windowsIpc.ts
index 355f88fbf79..acd99acaaa4 100644
--- a/src/vs/platform/windows/common/windowsIpc.ts
+++ b/src/vs/platform/windows/common/windowsIpc.ts
@@ -58,6 +58,7 @@ export class WindowsChannel implements IServerChannel {
 			case 'getRecentlyOpened': return this.service.getRecentlyOpened(arg);
 			case 'isFocused': return this.service.isFocused(arg);
 			case 'openExtensionDevelopmentHostWindow': return (this.service as any).openExtensionDevelopmentHostWindow(arg[0], arg[1]); // TODO@Isidor move
+			case 'getActiveWindowId': return this.service.getActiveWindowId();
 		}
 
 		throw new Error(`Call not found: ${command}`);
diff --git a/src/vs/platform/windows/electron-browser/windowsService.ts b/src/vs/platform/windows/electron-browser/windowsService.ts
index 7ba22274581..48b2e2aa4dc 100644
--- a/src/vs/platform/windows/electron-browser/windowsService.ts
+++ b/src/vs/platform/windows/electron-browser/windowsService.ts
@@ -57,4 +57,8 @@ export class WindowsService implements IWindowsService {
 	openExtensionDevelopmentHostWindow(args: ParsedArgs, env: IProcessEnvironment): Promise<void> {
 		return this.channel.call('openExtensionDevelopmentHostWindow', [args, env]);
 	}
+
+	getActiveWindowId(): Promise<number | undefined> {
+		return this.channel.call('getActiveWindowId');
+	}
 }
diff --git a/src/vs/platform/windows/electron-main/legacyWindowsMainService.ts b/src/vs/platform/windows/electron-main/legacyWindowsMainService.ts
index 7f8c9ace3c2..01adda9089c 100644
--- a/src/vs/platform/windows/electron-main/legacyWindowsMainService.ts
+++ b/src/vs/platform/windows/electron-main/legacyWindowsMainService.ts
@@ -3,7 +3,7 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { Disposable } from 'vs/base/common/lifecycle';
+import { Disposable, DisposableStore } from 'vs/base/common/lifecycle';
 import { assign } from 'vs/base/common/objects';
 import { URI } from 'vs/base/common/uri';
 import { IWindowsService, OpenContext } from 'vs/platform/windows/common/windows';
@@ -23,6 +23,10 @@ export class LegacyWindowsMainService extends Disposable implements IWindowsServ
 
 	_serviceBrand: undefined;
 
+	private readonly disposables = this._register(new DisposableStore());
+
+	private _activeWindowId: number | undefined;
+
 	readonly onWindowOpen: Event<number> = Event.filter(Event.fromNodeEventEmitter(app, 'browser-window-created', (_, w: BrowserWindow) => w.id), id => !!this.windowsMainService.getWindowById(id));
 	readonly onWindowBlur: Event<number> = Event.filter(Event.fromNodeEventEmitter(app, 'browser-window-blur', (_, w: BrowserWindow) => w.id), id => !!this.windowsMainService.getWindowById(id));
 	readonly onWindowMaximize: Event<number> = Event.filter(Event.fromNodeEventEmitter(app, 'browser-window-maximize', (_, w: BrowserWindow) => w.id), id => !!this.windowsMainService.getWindowById(id));
@@ -44,6 +48,10 @@ export class LegacyWindowsMainService extends Disposable implements IWindowsServ
 		super();
 
 		urlService.registerHandler(this);
+
+		// remember last active window id
+		Event.latch(Event.any(this.onWindowOpen, this.onWindowFocus))
+			(id => this._activeWindowId = id, null, this.disposables);
 	}
 
 	async addRecentlyOpened(recents: IRecent[]): Promise<void> {
@@ -88,6 +96,10 @@ export class LegacyWindowsMainService extends Disposable implements IWindowsServ
 		}
 	}
 
+	async getActiveWindowId(): Promise<number | undefined> {
+		return this._activeWindowId;
+	}
+
 	async handleURL(uri: URI): Promise<boolean> {
 
 		// Catch file URLs
diff --git a/src/vs/platform/windows/node/windows.ts b/src/vs/platform/windows/node/windows.ts
index b5e3f3f9c32..98bd1f8771e 100644
--- a/src/vs/platform/windows/node/windows.ts
+++ b/src/vs/platform/windows/node/windows.ts
@@ -14,18 +14,14 @@ export class ActiveWindowManager extends Disposable {
 	private firstActiveWindowIdPromise: CancelablePromise<number | undefined> | undefined;
 
 	private activeWindowId: number | undefined;
-	private _activeWindowId: number | undefined;
 
 	constructor(@IWindowsService windowsService: IWindowsService) {
 		super();
 
-		// remember last active window id
-		Event.latch(Event.any(windowsService.onWindowOpen, windowsService.onWindowFocus))(id => this._activeWindowId = id, null, this.disposables);
-
 		const onActiveWindowChange = Event.latch(Event.any(windowsService.onWindowOpen, windowsService.onWindowFocus));
 		onActiveWindowChange(this.setActiveWindow, this, this.disposables);
 
-		this.firstActiveWindowIdPromise = createCancelablePromise(_ => this.getActiveWindowId());
+		this.firstActiveWindowIdPromise = createCancelablePromise(_ => windowsService.getActiveWindowId());
 		this.firstActiveWindowIdPromise
 			.then(id => this.activeWindowId = typeof this.activeWindowId === 'number' ? this.activeWindowId : id)
 			.finally(this.firstActiveWindowIdPromise = undefined);
@@ -46,7 +42,4 @@ export class ActiveWindowManager extends Disposable {
 		return `window:${id}`;
 	}
 
-	private async getActiveWindowId(): Promise<number | undefined> {
-		return this._activeWindowId;
-	}
 }
diff --git a/src/vs/workbench/browser/web.simpleservices.ts b/src/vs/workbench/browser/web.simpleservices.ts
index 259c3d7e0da..58120dd86cf 100644
--- a/src/vs/workbench/browser/web.simpleservices.ts
+++ b/src/vs/workbench/browser/web.simpleservices.ts
@@ -165,6 +165,10 @@ export class SimpleWindowsService implements IWindowsService {
 			files: []
 		});
 	}
+
+	getActiveWindowId(): Promise<number | undefined> {
+		return Promise.resolve(0);
+	}
 }
 
 registerSingleton(IWindowsService, SimpleWindowsService);
diff --git a/src/vs/workbench/test/workbenchTestServices.ts b/src/vs/workbench/test/workbenchTestServices.ts
index 36457a11aed..d585c154e16 100644
--- a/src/vs/workbench/test/workbenchTestServices.ts
+++ b/src/vs/workbench/test/workbenchTestServices.ts
@@ -1280,6 +1280,10 @@ export class TestWindowsService implements IWindowsService {
 			files: []
 		});
 	}
+
+	getActiveWindowId(): Promise<number | undefined> {
+		return Promise.resolve(undefined);
+	}
 }
 
 export class TestTextResourceConfigurationService implements ITextResourceConfigurationService {