message: work for Dropdown Add the ability to select items by pressing the space bar.
diff: @@ -147,7 +147,7 @@ export class DropdownListModel extends Base {
  this.scrollToFocusedItem();
  event.preventDefault();
  event.stopPropagation();
  - } else if(this.popupModel.isVisible && event.keyCode === 13) {
  + } else if(this.popupModel.isVisible && (event.keyCode === 13 || event.keyCode === 32)) {
  this.listModel.selectFocusedItem();
  event.preventDefault();
  event.stopPropagation();
  