Here is an example in your dojo http://dojo.telerik.com/OdolO/3
When you try to use dataItem.selected property in ng-if statement then different visual bugs appear if you have nodes with children.
Please try to click on Item2 then expand it and click on any child of Item2. You will see that Item2 title disappeared. It works on 2014 Q3. We are unable to move from 2014 version to 2015 version because of different treeview visual bugs.