TreeGrid: filterData fails systematically complaining "(TypeError): _1 is undefined"

[d.cavestro]

Triggering TreeGrid.filterData() on a databound tree I get a com.google.gwt.core.client.JavaScriptException: (TypeError): _1 is undefined error message.
Doing the same on a ListGrid works.

...
{//datasource fields initialization
    final DataSourceTextField keyField = new DataSourceTextField ("id", "ID");
    keyField.setPrimaryKey (true);
    final DataSourceFloatField parentIdField = new DataSourceFloatField ("parentId", "Parent ID");
    parentIdField.setForeignKey ("id");
    final DataSourceFloatField nameField = new DataSourceFloatField ("name", "Name");
    
    dataSource.setFields (keyField, parentIdField, nameField);
}

//UI initialization
final TreeGrid treeGrid = new TreeGrid ();
treeGrid.setAutoFetchData (true);
treeGrid.setKeepParentsOnFilter (true);
treeGrid.setDataSource (dataSource);
//treeGrid.setLoadDataOnDemand (false);

{
    final DynamicForm form = new DynamicForm();
    final TextItem searchItem = new TextItem();
    searchItem.addKeyPressHandler(new KeyPressHandler() {

        @Override
        public void onKeyPress(final KeyPressEvent event) {
            if ("Enter".equals(event.getKeyName())) {
//              treeGrid.invalidateCache();
                treeGrid.filterData(new AdvancedCriteria("name", OperatorId.ICONTAINS, searchItem.getValueAsString()));
            }
        }
    });
    searchItem.setTitle("Search");
    form.setItems(searchItem);
}
...

Disabling keepParentsOnFilter seems to fix the problem, but when I try to expand the last child node (actually a leaf) all rows are discarded. Enabling loadDataOnDemand rows are kept.
So I have no way to filter a tree keeping the path to the root.

[ATTACH]4782[/ATTACH] is a complete test case entry point.
I've tested it on SmartGWT 3.1 [SmartClient Version: v8.3_2012-11-20/LGPL Development Only (built 2012-11-20)]

[d.cavestro]

Isomorphic, did I write a load of rubbish?
Having a working tree filtered that still keeps parents would be really useful... did I miss something from docs?

[d.cavestro]

I've found a workaround based on an external article.

It basically creates new data tree copies applying custom filter logic.

[bsoyluoglu]

Does anybody found a solution without using a second treegrid?
My issue is similar to the one above. The thing is,

grid.setLoadDataOnDemand(false); 
//grid.setDataFetchMode(FetchMode.LOCAL);
//grid.setKeepParentsOnFilter(true);

when filter button is pressed fetchdata is called, which is not the action I'm looking for. I want to achive client side filtering

if one of the above commented sections are added to the code. When filter button is press the exception is thrown by SmartGWT,

"(TypeError): _1 is undefined"