src/vs/workbench/contrib/codeEditor/browser/outline/documentSymbolsOutline.ts/DocumentSymbolsOutline/preview
class DocumentSymbolsOutline:	preview(entry: DocumentSymbolItem): IDisposable {
		if (!(entry instanceof OutlineElement)) {
			return Disposable.None;
		}

		const { symbol } = entry;
		this._editor.revealRangeInCenterIfOutsideViewport(symbol.range, ScrollType.Smooth);
		const ids = this._editor.deltaDecorations([], [{
			range: symbol.range,
			options: {
				description: 'document-symbols-outline-range-highlight',
				className: 'rangeHighlight',
				isWholeLine: true
			}
		}]);
		return toDisposable(() => this._editor.deltaDecorations(ids, []));
	}