src/vs/workbench/browser/parts/views/viewPane.ts/ViewPane/setFocusable
class ViewPane:	getActionViewItem(action: IAction, options?: IDropdownMenuActionViewItemOptions): IActionViewItem | undefined {
		if (action.id === VIEWPANE_FILTER_ACTION.id) {
			const that = this;
			return new class extends BaseActionViewItem {
				constructor() { super(null, action); }
				override setFocusable(): void { /* noop input elements are focusable by default */ }
				override get trapsArrowNavigation(): boolean { return true; }
				override render(container: HTMLElement): void {
					container.classList.add('viewpane-filter-container');
					append(container, that.getFilterWidget()!.element);
				}
			};
		}
		return createActionViewItem(this.instantiationService, action, { ...options, ...{ menuAsChild: action instanceof SubmenuItemAction } });
	}