code: function _keySelect() {
              var filteredChoices;
  
              if (lxSelect.choicesViewMode === 'panes') {
                  filteredChoices = lxSelect.panes[(lxSelect.panes.length - 1)];
                  if (!lxSelect.isLeaf(filteredChoices[lxSelect.activeChoiceIndex])) {
                      return;
                  }
              } else {
                  filteredChoices = $filter('filterChoices')(lxSelect.choices, lxSelect.filter, lxSelect.filterModel);
              }
  
              if (filteredChoices.length && filteredChoices[lxSelect.activeChoiceIndex]) {
                  lxSelect.toggleChoice(filteredChoices[lxSelect.activeChoiceIndex]);
              } else if (lxSelect.filterModel && lxSelect.allowNewValue) {
                  if (angular.isArray(getSelectedModel())) {
                      var value = angular.isFunction(lxSelect.newValueTransform) ? lxSelect.newValueTransform(lxSelect.filterModel) : lxSelect.filterModel;
                      var identical = getSelectedModel().some(function (item) {
                          return angular.equals(item, value);
                      });
  
                      if (!identical) {
                          lxSelect.getSelectedModel().push(value);
                      }
                  }
  
                  lxSelect.filterModel = undefined;
  
                  LxDropdownService.close('dropdown-' + lxSelect.uuid);
              }
          }
docs: When the enter key is pressed, select the currently active choice.