fixes #126964

src/vs/base/browser/ui/list/listWidget.ts

@@ -109,6 +109,7 @@ class TraitRenderer<T> implements IListRenderer<T, ITraitTemplateData>
 
 class Trait<T> implements ISpliceable<boolean>, IDisposable {
 
+	private length = 0;
 	private indexes: number[] = [];
 	private sortedIndexes: number[] = [];
 
@@ -125,16 +126,26 @@ class Trait<T> implements ISpliceable<boolean>, IDisposable {
 	constructor(private _trait: string) { }
 
 	splice(start: number, deleteCount: number, elements: boolean[]): void {
+		deleteCount = Math.max(0, Math.min(deleteCount, this.length - start));
+
 		const diff = elements.length - deleteCount;
 		const end = start + deleteCount;
-		const indexes = [
+		const sortedIndexes = [
 			...this.sortedIndexes.filter(i => i < start),
 			...elements.map((hasTrait, i) => hasTrait ? i + start : -1).filter(i => i !== -1),
 			...this.sortedIndexes.filter(i => i >= end).map(i => i + diff)
 		];
 
+		const length = this.length + diff;
+
+		if (this.sortedIndexes.length > 0 && sortedIndexes.length === 0) {
+			const first = this.sortedIndexes.find(index => index >= start) ?? length - 1;
+			sortedIndexes.push(Math.min(first, length - 1));
+		}
+
 		this.renderer.splice(start, deleteCount, elements.length);
-		this._set(indexes, indexes);
+		this._set(sortedIndexes, sortedIndexes);
+		this.length = length;
 	}
 
 	renderIndex(index: number, container: HTMLElement): void {
@@ -1472,6 +1483,11 @@ export class List<T> implements ISpliceable<T>, IThemable, IDisposable {
 		return firstOrDefault(this.anchor.get(), undefined);
 	}
 
+	getAnchorElement(): T | undefined {
+		const anchor = this.getAnchor();
+		return typeof anchor === 'undefined' ? undefined : this.element(anchor);
+	}
+
 	setFocus(indexes: number[], browserEvent?: UIEvent): void {
 		for (const index of indexes) {
 			if (index < 0 || index >= this.length) {

src/vs/base/browser/ui/tree/abstractTree.ts

@@ -1001,7 +1001,10 @@ class Trait<T> {
 		return this._nodeSet;
 	}
 
-	constructor(private identityProvider?: IIdentityProvider<T>) { }
+	constructor(
+		private getFirstViewElementWithTrait: () => ITreeNode<T, any> | undefined,
+		private identityProvider?: IIdentityProvider<T>
+	) { }
 
 	set(nodes: ITreeNode<T, any>[], browserEvent?: UIEvent): void {
 		if (!(browserEvent as any)?.__forceEvent && equals(this.nodes, nodes)) {
@@ -1072,6 +1075,14 @@ class Trait<T> {
 			}
 		}
 
+		if (this.nodes.length > 0 && nodes.length === 0) {
+			const node = this.getFirstViewElementWithTrait();
+
+			if (node) {
+				nodes.push(node);
+			}
+		}
+
 		this._set(nodes, true);
 	}
 
@@ -1321,9 +1332,9 @@ export abstract class AbstractTree<T, TFilterData, TRef> implements IDisposable
 			this.disposables.add(filter);
 		}
 
-		this.focus = new Trait(_options.identityProvider);
-		this.selection = new Trait(_options.identityProvider);
-		this.anchor = new Trait(_options.identityProvider);
+		this.focus = new Trait(() => this.view.getFocusedElements()[0], _options.identityProvider);
+		this.selection = new Trait(() => this.view.getSelectedElements()[0], _options.identityProvider);
+		this.anchor = new Trait(() => this.view.getAnchorElement(), _options.identityProvider);
 		this.view = new TreeNodeList(user, container, treeDelegate, this.renderers, this.focus, this.selection, this.anchor, { ...asListOptions(() => this.model, _options), tree: this });
 
 		this.model = this.createModel(user, this.view, _options);

src/vs/workbench/contrib/files/browser/explorerService.ts

@@ -347,7 +347,6 @@ export class ExplorerService implements IExplorerService {
 					const parent = element.parent;
 					// Remove Element from Parent (Model)
 					parent.removeChild(element);
-					this.view?.focusNeighbourIfItemFocused(element);
 					// Refresh Parent (View)
 					await this.view?.refresh(false, parent);
 				}

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

@@ -55,7 +55,6 @@ export interface IExplorerView {
 	setTreeInput(): Promise<void>;
 	itemsCopied(tats: ExplorerItem[], cut: boolean, previousCut: ExplorerItem[] | undefined): void;
 	setEditable(stat: ExplorerItem, isEditing: boolean): Promise<void>;
-	focusNeighbourIfItemFocused(item: ExplorerItem): void;
 	isItemVisible(item: ExplorerItem): boolean;
 	hasFocus(): boolean;
 }

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

@@ -611,30 +611,6 @@ export class ExplorerView extends ViewPane {
 		});
 	}
 
-	focusNeighbourIfItemFocused(item: ExplorerItem): void {
-		const focus = this.tree.getFocus();
-		if (focus.length !== 1) {
-			return;
-		}
-		const compressedController = this.renderer.getCompressedNavigationController(focus[0]) || this.renderer.getCompressedNavigationController(item);
-		const indexOfItem = compressedController?.items.indexOf(item) || -1;
-		const itemsCompressedTogether = compressedController && (compressedController.items.indexOf(focus[0]) >= 0) && (indexOfItem >= 0);
-
-		if (focus[0] === item || itemsCompressedTogether) {
-			if (itemsCompressedTogether && indexOfItem > 0 && item.parent) {
-				// In case of compact items just focus the parent if it is part of the compact item. So the focus stays
-				this.tree.setFocus([item.parent]);
-			} else {
-				this.tree.focusNext();
-				const newFocus = this.tree.getFocus();
-				if (newFocus.length === 1 && newFocus[0] === item) {
-					// There was no next item to focus, focus the previous one
-					this.tree.focusPrevious();
-				}
-			}
-		}
-	}
-
 	override getOptimalWidth(): number {
 		const parentNode = this.tree.getHTMLElement();
 		const childNodes = ([] as HTMLElement[]).slice.call(parentNode.querySelectorAll('.explorer-item .label-name')); // select all file labels