src/vs/workbench/api/common/extHostQuickOpen.ts/ExtHostQuickPick/activeItems
class ExtHostQuickPick:		set activeItems(activeItems: T[]) {
			this._activeItems = activeItems.filter(item => this._itemsToHandles.has(item));
			this.update({ activeItems: this._activeItems.map(item => this._itemsToHandles.get(item)) });
		}