fix microsoft#204994 (microsoft#205909)

Author: sandy081

src/vs/workbench/browser/parts/paneCompositeBar.ts

@@ -207,12 +207,6 @@ export class PaneCompositeBar extends Disposable {
 
 		if (to === this.location) {
 			this.onDidRegisterViewContainers([container]);
-
-			// Open view container if part is visible and there is no other view container opened
-			const visibleComposites = this.compositeBar.getVisibleComposites();
-			if (!this.paneCompositePart.getActivePaneComposite() && this.layoutService.isVisible(this.paneCompositePart.partId) && visibleComposites.length) {
-				this.paneCompositePart.openPaneComposite(visibleComposites[0].id);
-			}
 		}
 	}
 

src/vs/workbench/browser/parts/paneCompositePart.ts

@@ -180,7 +180,7 @@ export abstract class AbstractPaneCompositePart extends CompositePart<PaneCompos
 		this._register(this.onDidPaneCompositeClose(this.onDidClose, this));
 		this._register(this.globalActions.onDidChange(() => this.updateGlobalToolbarActions()));
 
-		this._register(this.registry.onDidDeregister(async (viewletDescriptor: PaneCompositeDescriptor) => {
+		this._register(this.registry.onDidDeregister((viewletDescriptor: PaneCompositeDescriptor) => {
 
 			const activeContainers = this.viewDescriptorService.getViewContainersByLocation(this.location)
 				.filter(container => this.viewDescriptorService.getViewContainerModel(container).activeViewDescriptors.length > 0);
@@ -189,7 +189,7 @@ export abstract class AbstractPaneCompositePart extends CompositePart<PaneCompos
 				if (this.getActiveComposite()?.getId() === viewletDescriptor.id) {
 					const defaultViewletId = this.viewDescriptorService.getDefaultViewContainer(this.location)?.id;
 					const containerToOpen = activeContainers.filter(c => c.id === defaultViewletId)[0] || activeContainers[0];
-					await this.openPaneComposite(containerToOpen.id);
+					this.doOpenPaneComposite(containerToOpen.id);
 				}
 			} else {
 				this.layoutService.setPartHidden(true, this.partId);

src/vs/workbench/services/views/browser/viewsService.ts

@@ -137,6 +137,11 @@ export class ViewsService extends Disposable implements IViewsService {
 	private onDidChangeContainerLocation(viewContainer: ViewContainer, from: ViewContainerLocation, to: ViewContainerLocation): void {
 		this.deregisterPaneComposite(viewContainer, from);
 		this.registerPaneComposite(viewContainer, to);
+
+		// Open view container if part is visible and there is only one view container in location
+		if (this.layoutService.isVisible(getPartByLocation(to)) && this.viewDescriptorService.getViewContainersByLocation(to).length === 1) {
+			this.openViewContainer(viewContainer.id);
+		}
 	}
 
 	private onViewDescriptorsAdded(views: ReadonlyArray<IViewDescriptor>, container: ViewContainer): void {