code: function _handleMatchSelection(key){
          var caretPosition = _getCaretPosition($select.searchInput[0]),
              length = $select.selected.length,
              // none  = -1,
              first = 0,
              last  = length-1,
              curr  = $selectMultiple.activeMatchIndex,
              next  = $selectMultiple.activeMatchIndex+1,
              prev  = $selectMultiple.activeMatchIndex-1,
              newIndex = curr;
  
          if(caretPosition > 0 || ($select.search.length && key == KEY.RIGHT)) return false;
  
          $select.close();
  
          function getNewActiveMatchIndex(){
            switch(key){
              case KEY.LEFT:
                // Select previous/first item
                if(~$selectMultiple.activeMatchIndex) return prev;
                // Select last item
                else return last;
                break;
              case KEY.RIGHT:
                // Open drop-down
                if(!~$selectMultiple.activeMatchIndex || curr === last){
                  $select.activate();
                  return false;
                }
                // Select next/last item
                else return next;
                break;
              case KEY.BACKSPACE:
                // Remove selected item and select previous/first
                if(~$selectMultiple.activeMatchIndex){
                  if($selectMultiple.removeChoice(curr)) {
                    return prev;
                  } else {
                    return curr;
                  }
  
                } else {
                  // If nothing yet selected, select last item
                  return last;
                }
                break;
              case KEY.DELETE:
                // Remove selected item and select next item
                if(~$selectMultiple.activeMatchIndex){
                  $selectMultiple.removeChoice($selectMultiple.activeMatchIndex);
                  return curr;
                }
                else return false;
            }
          }
  
          newIndex = getNewActiveMatchIndex();
  
          if(!$select.selected.length || newIndex === false) $selectMultiple.activeMatchIndex = -1;
          else $selectMultiple.activeMatchIndex = Math.min(last,Math.max(first,newIndex));
  
          return true;
        }
docs: Handles selected options in "multiple" mode