gistfile1.js

  rowHeight: 21,
  customRowHeight: 32,
  useCustomRowHeight: YES,
  
  customRowHeightIndexes: function(){
    if(!this.get('useCustomRowHeight')) return null;
    var ret = SC.IndexSet.create(), idx, len, nextHeaderIdx = 0;
    var content = this.getPath('content.treeItemChildren');
    if (content) {
      len = content.get('length');
      for (var i=0; i < len; i++) {
        if (content[i].treeItemChildren.length > 0) {
          idx = i;
          if (idx === 0) {
            ret.add(idx);
          }else{
            ret.add(nextHeaderIdx);
          }
        }
        nextHeaderIdx = content[i].treeItemChildren.length + 1 + nextHeaderIdx;
      }
    }
    return ret.freeze();
  }.property('useCustomRowHeight').cacheable(),
  
  contentIndexRowHeight: function(view, content, index){
    var rowHeight = this.get('customRowHeight');
    var set = this.get('customRowHeightIndexes');
    return (set && set.contains(index)) ? rowHeight : this.get('rowHeight');
  }