parts: do not layout if not visible

fixes #39185

src/vs/workbench/browser/parts/activitybar/activitybarPart.ts

@@ -18,7 +18,7 @@ import { Part } from 'vs/workbench/browser/part';
 import { GlobalActivityActionItem, GlobalActivityAction, ViewletActivityAction, ToggleViewletAction } from 'vs/workbench/browser/parts/activitybar/activitybarActions';
 import { IViewletService } from 'vs/workbench/services/viewlet/browser/viewlet';
 import { IBadge } from 'vs/workbench/services/activity/common/activity';
-import { IPartService, Position as SideBarPosition } from 'vs/workbench/services/part/common/partService';
+import { IPartService, Parts, Position as SideBarPosition } from 'vs/workbench/services/part/common/partService';
 import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
 import { IContextMenuService } from 'vs/platform/contextview/browser/contextView';
 import { StandardMouseEvent } from 'vs/base/browser/mouseEvent';
@@ -184,6 +184,9 @@ export class ActivitybarPart extends Part {
 	 * Layout title, content and status area in the given dimension.
 	 */
 	public layout(dimension: Dimension): Dimension[] {
+		if (!this.partService.isVisible(Parts.ACTIVITYBAR_PART)) {
+			return [dimension];
+		}
 
 		// Pass to super
 		const sizes = super.layout(dimension);

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

@@ -213,6 +213,9 @@ export class PanelPart extends CompositePart<Panel> implements IPanelService {
 	}
 
 	public layout(dimension: Dimension): Dimension[] {
+		if (!this.partService.isVisible(Parts.PANEL_PART)) {
+			return [dimension];
+		}
 
 		if (this.partService.getPanelPosition() === Position.RIGHT) {
 			// Take into account the 1px border when layouting

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

@@ -29,6 +29,7 @@ import { IThemeService } from 'vs/platform/theme/common/themeService';
 import { contrastBorder } from 'vs/platform/theme/common/colorRegistry';
 import { SIDE_BAR_TITLE_FOREGROUND, SIDE_BAR_BACKGROUND, SIDE_BAR_FOREGROUND, SIDE_BAR_BORDER } from 'vs/workbench/common/theme';
 import { ToggleSidebarVisibilityAction } from 'vs/workbench/browser/actions/toggleSidebarVisibility';
+import { Dimension } from 'vs/base/browser/builder';
 
 export class SidebarPart extends CompositePart<Viewlet> {
 
@@ -128,6 +129,14 @@ export class SidebarPart extends CompositePart<Viewlet> {
 		return this.hideActiveComposite().then(composite => void 0);
 	}
 
+	public layout(dimension: Dimension): Dimension[] {
+		if (!this.partService.isVisible(Parts.SIDEBAR_PART)) {
+			return [dimension];
+		}
+
+		return super.layout(dimension);
+	}
+
 	protected getTitleAreaContextMenuActions(): IAction[] {
 		const contextMenuActions = super.getTitleAreaContextMenuActions();
 		if (contextMenuActions.length) {