message: don't toggle item when dropdown is closed
diff: @@ -362,7 +362,9 @@ export class NgSelectComponent implements OnInit, ControlValueAccessor {
  }
  private handleEnter($event: KeyboardEvent) {
  + if (this.isOpen) {
  this.toggle(this.itemsList.markedItem);
  + }
  $event.preventDefault();
  }
  