Wrong Parent ID in connector filter, is it bug?

Trying to look at the sample treegrid (dhtmlxConnector/samples/treegrid/02_dynamic_loading.html) and noticed a problem there:

adding any text in the filter result in a query where parentid is always 0:

SELECT taskId,parentId,taskName,duration,complete FROM tasks WHERE taskName LIKE ‘%task%’ AND parentId = ‘0’

which means that only first level is used thus defeating the whole purpose of filtering the tree.
Am I missing something, is there a way to set the level for filtering or to remove this parent_id from WHERE altogether?

You can use setFilrationLevel() method to configure the level of the filtering.

Here is the tutorial about this technique:
docs.dhtmlx.com/doku.php?id=dhtm … n_treegrid