A better solution is to extend a new method. The code below is the simple implementation of the 'getFolders' method.
$.extend($.fn.tree.methods,{
getFolders: function(jq, target){
var nodes = [];
var ul = $(target).length ? $(target).next() : jq;
ul.find("div.tree-node:has(span.tree-folder)").each(function(){
nodes.push(jq.tree('getNode',this));
});
return nodes;
}
});
To get the selected node's child folders, try this:
var node = $('#tt').tree('getSelected');
var folders = $('#tt').tree('getFolders', node.target);
console.log(folders);