fixes #68663

src/vs/workbench/browser/layout.ts

@@ -712,6 +712,14 @@ export abstract class Layout extends Disposable implements IWorkbenchLayoutServi
 			this.workbenchGrid = new Grid(this.editorPartView, { proportionalLayout: false });
 
 			this.container.prepend(this.workbenchGrid.element);
+
+			this._register((this.sideBarPartView as SidebarPart).onDidVisibilityChange((visible) => {
+				this.setSideBarHidden(!visible, true);
+			}));
+
+			this._register((this.panelPartView as PanelPart).onDidVisibilityChange((visible) => {
+				this.setPanelHidden(!visible, true);
+			}));
 		} else {
 			this.workbenchGrid = instantiationService.createInstance(
 				WorkbenchLegacyLayout,

src/vs/workbench/browser/parts/panel/panelPart.ts

@@ -5,7 +5,7 @@
 
 import 'vs/css!./media/panelpart';
 import { IAction } from 'vs/base/common/actions';
-import { Event } from 'vs/base/common/event';
+import { Event, Emitter } from 'vs/base/common/event';
 import { Registry } from 'vs/platform/registry/common/platform';
 import { ActionsOrientation } from 'vs/base/browser/ui/actionbar/actionbar';
 import { IPanel, ActivePanelContext, PanelFocusContext } from 'vs/workbench/common/panel';
@@ -64,6 +64,9 @@ export class PanelPart extends CompositePart<Panel> implements IPanelService {
 	get onDidPanelOpen(): Event<{ panel: IPanel, focus: boolean }> { return Event.map(this.onDidCompositeOpen.event, compositeOpen => ({ panel: compositeOpen.composite, focus: compositeOpen.focus })); }
 	get onDidPanelClose(): Event<IPanel> { return this.onDidCompositeClose.event; }
 
+	private _onDidVisibilityChange = this._register(new Emitter<boolean>());
+	get onDidVisibilityChange(): Event<boolean> { return this._onDidVisibilityChange.event; }
+
 	private activePanelContextKey: IContextKey<string>;
 	private panelFocusContextKey: IContextKey<boolean>;
 
@@ -433,6 +436,10 @@ export class PanelPart extends CompositePart<Panel> implements IPanelService {
 		this.storageService.store(PanelPart.PINNED_PANELS, value, StorageScope.GLOBAL);
 	}
 
+	setVisible(visible: boolean): void {
+		this._onDidVisibilityChange.fire(visible);
+	}
+
 	toJSON(): object {
 		return {
 			type: Parts.PANEL_PART

src/vs/workbench/browser/parts/sidebar/sidebarPart.ts

@@ -51,6 +51,9 @@ export class SidebarPart extends CompositePart<Viewlet> implements IViewletServi
 
 	get onDidViewletRegister(): Event<ViewletDescriptor> { return <Event<ViewletDescriptor>>this.viewletRegistry.onDidRegister; }
 
+	private _onDidVisibilityChange = this._register(new Emitter<boolean>());
+	get onDidVisibilityChange(): Event<boolean> { return this._onDidVisibilityChange.event; }
+
 	private _onDidViewletDeregister = this._register(new Emitter<ViewletDescriptor>());
 	get onDidViewletDeregister(): Event<ViewletDescriptor> { return this._onDidViewletDeregister.event; }
 
@@ -253,6 +256,10 @@ export class SidebarPart extends CompositePart<Viewlet> implements IViewletServi
 		}
 	}
 
+	setVisible(visible: boolean): void {
+		this._onDidVisibilityChange.fire(visible);
+	}
+
 	toJSON(): object {
 		return {
 			type: Parts.SIDEBAR_PART