src/vs/workbench/contrib/search/browser/searchResultsView.ts/SearchDND/getDragLabel
class SearchDND:	getDragLabel?(elements: RenderableMatch[]): string | undefined {
		if (elements.length > 1) {
			return String(elements.length);
		}

		const element = elements[0];
		return element instanceof FileMatch ?
			resources.basename(element.resource) :
			undefined;
	}