fixes #65585

src/vs/base/browser/ui/splitview/panelview.ts

@@ -42,9 +42,10 @@ export abstract class Panel implements IView {
 	private static readonly HEADER_SIZE = 22;
 
 	readonly element: HTMLElement;
+	private header: HTMLElement;
+	private body: HTMLElement;
 
 	protected _expanded: boolean;
-	protected disposables: IDisposable[] = [];
 
 	private expandedSize: number | undefined = undefined;
 	private _headerVisible = true;
@@ -52,12 +53,13 @@ export abstract class Panel implements IView {
 	private _maximumBodySize: number;
 	private ariaHeaderLabel: string;
 	private styles: IPanelStyles = {};
-
-	private header: HTMLElement;
+	private animationTimer: number | null = null;
 
 	private _onDidChange = new Emitter<number | undefined>();
 	readonly onDidChange: Event<number | undefined> = this._onDidChange.event;
 
+	protected disposables: IDisposable[] = [];
+
 	get draggableElement(): HTMLElement {
 		return this.header;
 	}
@@ -133,6 +135,15 @@ export abstract class Panel implements IView {
 		this.updateHeader();
 		this._onDidChange.fire(expanded ? this.expandedSize : undefined);
 
+		if (expanded) {
+			clearTimeout(this.animationTimer);
+			append(this.element, this.body);
+		} else {
+			this.animationTimer = window.setTimeout(() => {
+				this.body.remove();
+			}, 200);
+		}
+
 		return true;
 	}
 
@@ -179,15 +190,8 @@ export abstract class Panel implements IView {
 		domEvent(this.header, 'click')
 			(() => this.setExpanded(!this.isExpanded()), null, this.disposables);
 
-		// TODO@Joao move this down to panelview
-		// onHeaderKeyDown.filter(e => e.keyCode === KeyCode.UpArrow)
-		// 	.event(focusPrevious, this, this.disposables);
-
-		// onHeaderKeyDown.filter(e => e.keyCode === KeyCode.DownArrow)
-		// 	.event(focusNext, this, this.disposables);
-
-		const body = append(this.element, $('.panel-body'));
-		this.renderBody(body);
+		this.body = append(this.element, $('.panel-body'));
+		this.renderBody(this.body);
 	}
 
 	layout(height: number): void {

src/vs/workbench/contrib/files/browser/views/openEditorsView.ts

@@ -280,7 +280,6 @@ export class OpenEditorsView extends ViewletPanel {
 		this.listRefreshScheduler.schedule(0);
 
 		this.disposables.push(this.onDidChangeBodyVisibility(visible => {
-			this.updateListVisibility(visible);
 			if (visible && this.needsRefresh) {
 				this.listRefreshScheduler.schedule(0);
 			}
@@ -310,16 +309,6 @@ export class OpenEditorsView extends ViewletPanel {
 		}
 	}
 
-	private updateListVisibility(isVisible: boolean): void {
-		if (this.list) {
-			if (isVisible) {
-				dom.show(this.list.getHTMLElement());
-			} else {
-				dom.hide(this.list.getHTMLElement()); // make sure the list goes out of the tabindex world by hiding it
-			}
-		}
-	}
-
 	private get showGroups(): boolean {
 		return this.editorGroupService.groups.length > 1;
 	}